diff --git a/httpcore/adapters/redirects.py b/httpcore/adapters/redirects.py
index 0a79b4c9..08639cd8 100644
--- a/httpcore/adapters/redirects.py
+++ b/httpcore/adapters/redirects.py
@@ -65,7 +65,7 @@ class RedirectAdapter(Adapter):
         url = self.redirect_url(request, response)
         headers = self.redirect_headers(request, url)
         content = self.redirect_content(request, method)
-        return Request(method=method, url=url, headers=headers, content=content)
+        return Request(method=method, url=url, headers=headers, data=content)
 
     def redirect_method(self, request: Request, response: Response) -> str:
         """
diff --git a/httpcore/backends/sync.py b/httpcore/backends/sync.py
index ae831941..2bb582a5 100644
--- a/httpcore/backends/sync.py
+++ b/httpcore/backends/sync.py
@@ -14,10 +14,11 @@ from ..config import (
 )
 from ..models import (
     URL,
-    ByteOrByteStream,
     Headers,
     HeaderTypes,
+    QueryParamTypes,
     Request,
+    RequestData,
     Response,
     URLTypes,
 )
@@ -100,14 +101,17 @@ class SyncClient:
         method: str,
         url: URLTypes,
         *,
-        content: ByteOrByteStream = b"",
+        data: RequestData = b"",
+        query_params: QueryParamTypes = None,
         headers: HeaderTypes = None,
         stream: bool = False,
         allow_redirects: bool = True,
         ssl: SSLConfig = None,
         timeout: TimeoutConfig = None,
     ) -> SyncResponse:
-        request = Request(method, url, headers=headers, content=content)
+        request = Request(
+            method, url, data=data, query_params=query_params, headers=headers
+        )
         self.prepare_request(request)
         response = self.send(
             request,
@@ -122,6 +126,7 @@ class SyncClient:
         self,
         url: URLTypes,
         *,
+        query_params: QueryParamTypes = None,
         headers: HeaderTypes = None,
         stream: bool = False,
         allow_redirects: bool = True,
@@ -142,6 +147,7 @@ class SyncClient:
         self,
         url: URLTypes,
         *,
+        query_params: QueryParamTypes = None,
         headers: HeaderTypes = None,
         stream: bool = False,
         allow_redirects: bool = True,
@@ -162,6 +168,7 @@ class SyncClient:
         self,
         url: URLTypes,
         *,
+        query_params: QueryParamTypes = None,
         headers: HeaderTypes = None,
         stream: bool = False,
         allow_redirects: bool = False,  #  Note: Differs to usual default.
@@ -182,7 +189,8 @@ class SyncClient:
         self,
         url: URLTypes,
         *,
-        content: ByteOrByteStream = b"",
+        data: RequestData = b"",
+        query_params: QueryParamTypes = None,
         headers: HeaderTypes = None,
         stream: bool = False,
         allow_redirects: bool = True,
@@ -192,7 +200,7 @@ class SyncClient:
         return self.request(
             "POST",
             url,
-            content=content,
+            data=data,
             headers=headers,
             stream=stream,
             allow_redirects=allow_redirects,
@@ -204,7 +212,8 @@ class SyncClient:
         self,
         url: URLTypes,
         *,
-        content: ByteOrByteStream = b"",
+        data: RequestData = b"",
+        query_params: QueryParamTypes = None,
         headers: HeaderTypes = None,
         stream: bool = False,
         allow_redirects: bool = True,
@@ -214,7 +223,7 @@ class SyncClient:
         return self.request(
             "PUT",
             url,
-            content=content,
+            data=data,
             headers=headers,
             stream=stream,
             allow_redirects=allow_redirects,
@@ -226,7 +235,8 @@ class SyncClient:
         self,
         url: URLTypes,
         *,
-        content: ByteOrByteStream = b"",
+        data: RequestData = b"",
+        query_params: QueryParamTypes = None,
         headers: HeaderTypes = None,
         stream: bool = False,
         allow_redirects: bool = True,
@@ -236,7 +246,7 @@ class SyncClient:
         return self.request(
             "PATCH",
             url,
-            content=content,
+            data=data,
             headers=headers,
             stream=stream,
             allow_redirects=allow_redirects,
@@ -248,7 +258,8 @@ class SyncClient:
         self,
         url: URLTypes,
         *,
-        content: ByteOrByteStream = b"",
+        data: RequestData = b"",
+        query_params: QueryParamTypes = None,
         headers: HeaderTypes = None,
         stream: bool = False,
         allow_redirects: bool = True,
@@ -258,7 +269,7 @@ class SyncClient:
         return self.request(
             "DELETE",
             url,
-            content=content,
+            data=data,
             headers=headers,
             stream=stream,
             allow_redirects=allow_redirects,
diff --git a/httpcore/client.py b/httpcore/client.py
index a3e31f1d..16925b31 100644
--- a/httpcore/client.py
+++ b/httpcore/client.py
@@ -17,10 +17,10 @@ from .config import (
 from .dispatch.connection_pool import ConnectionPool
 from .models import (
     URL,
-    ByteOrByteStream,
     HeaderTypes,
     QueryParamTypes,
     Request,
+    RequestData,
     Response,
     URLTypes,
 )
@@ -49,7 +49,7 @@ class Client:
         method: str,
         url: URLTypes,
         *,
-        content: ByteOrByteStream = b"",
+        data: RequestData = b"",
         query_params: QueryParamTypes = None,
         headers: HeaderTypes = None,
         stream: bool = False,
@@ -58,7 +58,7 @@ class Client:
         timeout: TimeoutConfig = None,
     ) -> Response:
         request = Request(
-            method, url, query_params=query_params, headers=headers, content=content
+            method, url, data=data, query_params=query_params, headers=headers
         )
         self.prepare_request(request)
         response = await self.send(
@@ -140,7 +140,7 @@ class Client:
         self,
         url: URLTypes,
         *,
-        content: ByteOrByteStream = b"",
+        data: RequestData = b"",
         query_params: QueryParamTypes = None,
         headers: HeaderTypes = None,
         stream: bool = False,
@@ -151,7 +151,7 @@ class Client:
         return await self.request(
             "POST",
             url,
-            content=content,
+            data=data,
             query_params=query_params,
             headers=headers,
             stream=stream,
@@ -164,7 +164,7 @@ class Client:
         self,
         url: URLTypes,
         *,
-        content: ByteOrByteStream = b"",
+        data: RequestData = b"",
         query_params: QueryParamTypes = None,
         headers: HeaderTypes = None,
         stream: bool = False,
@@ -175,7 +175,7 @@ class Client:
         return await self.request(
             "PUT",
             url,
-            content=content,
+            data=data,
             query_params=query_params,
             headers=headers,
             stream=stream,
@@ -188,7 +188,7 @@ class Client:
         self,
         url: URLTypes,
         *,
-        content: ByteOrByteStream = b"",
+        data: RequestData = b"",
         query_params: QueryParamTypes = None,
         headers: HeaderTypes = None,
         stream: bool = False,
@@ -199,7 +199,7 @@ class Client:
         return await self.request(
             "PATCH",
             url,
-            content=content,
+            data=data,
             query_params=query_params,
             headers=headers,
             stream=stream,
@@ -212,7 +212,7 @@ class Client:
         self,
         url: URLTypes,
         *,
-        content: ByteOrByteStream = b"",
+        data: RequestData = b"",
         query_params: QueryParamTypes = None,
         headers: HeaderTypes = None,
         stream: bool = False,
@@ -223,7 +223,7 @@ class Client:
         return await self.request(
             "DELETE",
             url,
-            content=content,
+            data=data,
             query_params=query_params,
             headers=headers,
             stream=stream,
diff --git a/httpcore/interfaces.py b/httpcore/interfaces.py
index 2ada76c8..5903c454 100644
--- a/httpcore/interfaces.py
+++ b/httpcore/interfaces.py
@@ -2,7 +2,15 @@ import typing
 from types import TracebackType
 
 from .config import TimeoutConfig
-from .models import URL, ByteOrByteStream, HeaderTypes, Request, Response, URLTypes
+from .models import (
+    URL,
+    HeaderTypes,
+    QueryParamTypes,
+    Request,
+    RequestData,
+    Response,
+    URLTypes,
+)
 
 OptionalTimeout = typing.Optional[TimeoutConfig]
 
@@ -21,11 +29,14 @@ class Adapter:
         method: str,
         url: URLTypes,
         *,
+        data: RequestData = b"",
+        query_params: QueryParamTypes = None,
         headers: HeaderTypes = None,
-        content: ByteOrByteStream = b"",
         **options: typing.Any,
     ) -> Response:
-        request = Request(method, url, headers=headers, content=content)
+        request = Request(
+            method, url, data=data, query_params=query_params, headers=headers
+        )
         self.prepare_request(request)
         response = await self.send(request, **options)
         return response
diff --git a/httpcore/models.py b/httpcore/models.py
index 5eeec460..251f6265 100644
--- a/httpcore/models.py
+++ b/httpcore/models.py
@@ -44,7 +44,9 @@ HeaderTypes = typing.Union[
     typing.List[typing.Tuple[typing.AnyStr, typing.AnyStr]],
 ]
 
-ByteOrByteStream = typing.Union[bytes, typing.AsyncIterator[bytes]]
+RequestData = typing.Union[dict, bytes, typing.AsyncIterator[bytes]]
+
+ResponseContent = typing.Union[bytes, typing.AsyncIterator[bytes]]
 
 
 class URL:
@@ -197,7 +199,7 @@ class Origin:
         return hash((self.is_ssl, self.host, self.port))
 
 
-class QueryParams(typing.Mapping):
+class QueryParams(typing.Mapping[str, str]):
     """
     URL query parameters, as a multi-dict.
     """
@@ -456,19 +458,24 @@ class Request:
         method: str,
         url: typing.Union[str, URL],
         *,
+        data: RequestData = b"",
         query_params: QueryParamTypes = None,
         headers: HeaderTypes = None,
-        content: ByteOrByteStream = b"",
     ):
         self.method = method.upper()
         self.url = URL(url, query_params=query_params)
-        if isinstance(content, bytes):
+        self.headers = Headers(headers)
+
+        if isinstance(data, bytes):
             self.is_streaming = False
-            self.content = content
+            self.content = data
+        elif isinstance(data, dict):
+            self.is_streaming = False
+            self.content = urlencode(data, doseq=True).encode("utf-8")
+            self.headers["Content-Type"] = "application/x-www-form-urlencoded"
         else:
             self.is_streaming = True
-            self.content_aiter = content
-        self.headers = Headers(headers)
+            self.content_aiter = data
 
     async def read(self) -> bytes:
         """
@@ -532,7 +539,7 @@ class Response:
         reason_phrase: str = None,
         protocol: str = None,
         headers: HeaderTypes = None,
-        content: ByteOrByteStream = b"",
+        content: ResponseContent = b"",
         on_close: typing.Callable = None,
         request: Request = None,
         history: typing.List["Response"] = None,
diff --git a/tests/adapters/test_redirects.py b/tests/adapters/test_redirects.py
index 574b6dc5..94e5a745 100644
--- a/tests/adapters/test_redirects.py
+++ b/tests/adapters/test_redirects.py
@@ -222,8 +222,8 @@ async def test_same_domain_redirect():
 async def test_body_redirect():
     client = RedirectAdapter(MockDispatch())
     url = "https://example.org/redirect_body"
-    content = b"Example request body"
-    response = await client.request("POST", url, content=content)
+    data = b"Example request body"
+    response = await client.request("POST", url, data=data)
     data = json.loads(response.content.decode())
     assert response.url == URL("https://example.org/redirect_body_target")
     assert data == {"body": "Example request body"}
@@ -238,4 +238,4 @@ async def test_cannot_redirect_streaming_body():
         yield b"Example request body"
 
     with pytest.raises(RedirectBodyUnavailable):
-        await client.request("POST", url, content=streaming_body())
+        await client.request("POST", url, data=streaming_body())
diff --git a/tests/dispatch/test_http2.py b/tests/dispatch/test_http2.py
index 0adf7b8a..b9bf8ccf 100644
--- a/tests/dispatch/test_http2.py
+++ b/tests/dispatch/test_http2.py
@@ -92,7 +92,7 @@ async def test_http2_get_request():
 async def test_http2_post_request():
     server = MockServer()
     async with httpcore.HTTP2Connection(reader=server, writer=server) as conn:
-        response = await conn.request("POST", "http://example.org", content=b"<data>")
+        response = await conn.request("POST", "http://example.org", data=b"<data>")
     assert response.status_code == 200
     assert json.loads(response.content) == {
         "method": "POST",
diff --git a/tests/models/test_requests.py b/tests/models/test_requests.py
index 98eea510..f010db8c 100644
--- a/tests/models/test_requests.py
+++ b/tests/models/test_requests.py
@@ -17,7 +17,7 @@ def test_host_header():
 
 
 def test_content_length_header():
-    request = httpcore.Request("POST", "http://example.org", content=b"test 123")
+    request = httpcore.Request("POST", "http://example.org", data=b"test 123")
     request.prepare()
     assert request.headers == httpcore.Headers(
         [
@@ -28,13 +28,27 @@ def test_content_length_header():
     )
 
 
+def test_url_encoded_data():
+    request = httpcore.Request("POST", "http://example.org", data={"test": "123"})
+    request.prepare()
+    assert request.headers == httpcore.Headers(
+        [
+            (b"host", b"example.org"),
+            (b"content-length", b"8"),
+            (b"accept-encoding", b"deflate, gzip, br"),
+            (b"content-type", b"application/x-www-form-urlencoded"),
+        ]
+    )
+    assert request.content == b"test=123"
+
+
 def test_transfer_encoding_header():
     async def streaming_body(data):
         yield data  # pragma: nocover
 
-    content = streaming_body(b"test 123")
+    data = streaming_body(b"test 123")
 
-    request = httpcore.Request("POST", "http://example.org", content=content)
+    request = httpcore.Request("POST", "http://example.org", data=data)
     request.prepare()
     assert request.headers == httpcore.Headers(
         [
@@ -69,12 +83,10 @@ def test_override_content_length_header():
     async def streaming_body(data):
         yield data  # pragma: nocover
 
-    content = streaming_body(b"test 123")
+    data = streaming_body(b"test 123")
     headers = [(b"content-length", b"8")]
 
-    request = httpcore.Request(
-        "POST", "http://example.org", content=content, headers=headers
-    )
+    request = httpcore.Request("POST", "http://example.org", data=data, headers=headers)
     request.prepare()
     assert request.headers == httpcore.Headers(
         [
diff --git a/tests/test_client.py b/tests/test_client.py
index 1d33379c..cd6437ae 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -16,7 +16,7 @@ async def test_get(server):
 async def test_post(server):
     url = "http://127.0.0.1:8000/"
     async with httpcore.Client() as client:
-        response = await client.post(url, content=b"Hello, world!")
+        response = await client.post(url, data=b"Hello, world!")
     assert response.status_code == 200
 
 
@@ -47,7 +47,7 @@ async def test_stream_request(server):
 
     async with httpcore.Client() as client:
         response = await client.request(
-            "POST", "http://127.0.0.1:8000/", content=hello_world()
+            "POST", "http://127.0.0.1:8000/", data=hello_world()
         )
     assert response.status_code == 200
 
diff --git a/tests/test_sync.py b/tests/test_sync.py
index 99b6c188..b5f55cef 100644
--- a/tests/test_sync.py
+++ b/tests/test_sync.py
@@ -35,7 +35,7 @@ def test_get(server):
 @threadpool
 def test_post(server):
     with httpcore.SyncClient() as http:
-        response = http.post("http://127.0.0.1:8000/", content=b"Hello, world!")
+        response = http.post("http://127.0.0.1:8000/", data=b"Hello, world!")
     assert response.status_code == 200
     assert response.reason_phrase == "OK"