diff --git a/conformance/results/mypy/protocols_definition.toml b/conformance/results/mypy/protocols_definition.toml
index 717b8cad5..e34a5fbba 100644
--- a/conformance/results/mypy/protocols_definition.toml
+++ b/conformance/results/mypy/protocols_definition.toml
@@ -51,6 +51,9 @@ protocols_definition.py:340: error: Incompatible types in assignment (expression
 protocols_definition.py:340: note: Protocol member Template6.val1 expected settable variable, got read-only attribute
 protocols_definition.py:341: error: Incompatible types in assignment (expression has type "Concrete6_Bad3", variable has type "Template6")  [assignment]
 protocols_definition.py:341: note: Protocol member Template6.val1 expected settable variable, got read-only attribute
+protocols_definition.py:369: error: Incompatible types in assignment (expression has type "Concrete7_Bad1", variable has type "Template7")  [assignment]
+protocols_definition.py:369: note: Protocol member Template7.val1 expected class variable, got instance variable
+protocols_definition.py:370: error: Incompatible types in assignment (expression has type "Concrete7_Bad2", variable has type "Template7")  [assignment]
 """
 conformance_automated = "Fail"
 errors_diff = """
diff --git a/conformance/results/pycroscope/protocols_definition.toml b/conformance/results/pycroscope/protocols_definition.toml
index 506df6a7a..d5e5f2dc7 100644
--- a/conformance/results/pycroscope/protocols_definition.toml
+++ b/conformance/results/pycroscope/protocols_definition.toml
@@ -1,5 +1,10 @@
-conformance_automated = "Pass"
+conformance_automated = "Fail"
+conformant = "Partial"
+notes = """
+Incorrectly accepts an instance-only attribute as satisfying a `ClassVar` protocol member.
+"""
 errors_diff = """
+Line 369: Expected 1 errors
 """
 output = """
 ./protocols_definition.py:30:10: Incompatible argument type for things: expected collections.abc.Iterable[./protocols_definition.py.SupportsClose] but got Literal[[1]] [incompatible_argument]
@@ -23,4 +28,5 @@ output = """
 ./protocols_definition.py:339:0: Incompatible assignment: expected ./protocols_definition.py.Template6, got ./protocols_definition.py.Concrete6_Bad1 [incompatible_assignment]
 ./protocols_definition.py:340:0: Incompatible assignment: expected ./protocols_definition.py.Template6, got ./protocols_definition.py.Concrete6_Bad2 [incompatible_assignment]
 ./protocols_definition.py:341:0: Incompatible assignment: expected ./protocols_definition.py.Template6, got ./protocols_definition.py.Concrete6_Bad3 [incompatible_assignment]
+./protocols_definition.py:370:0: Incompatible assignment: expected ./protocols_definition.py.Template7, got ./protocols_definition.py.Concrete7_Bad2 [incompatible_assignment]
 """
diff --git a/conformance/results/pyrefly/protocols_definition.toml b/conformance/results/pyrefly/protocols_definition.toml
index 766d78c3f..a02940d9b 100644
--- a/conformance/results/pyrefly/protocols_definition.toml
+++ b/conformance/results/pyrefly/protocols_definition.toml
@@ -24,4 +24,6 @@ ERROR protocols_definition.py:289:22-38: `Concrete5_Bad5` is not assignable to `
 ERROR protocols_definition.py:339:22-38: `Concrete6_Bad1` is not assignable to `Template6` [bad-assignment]
 ERROR protocols_definition.py:340:22-38: `Concrete6_Bad2` is not assignable to `Template6` [bad-assignment]
 ERROR protocols_definition.py:341:22-38: `Concrete6_Bad3` is not assignable to `Template6` [bad-assignment]
+ERROR protocols_definition.py:369:22-38: `Concrete7_Bad1` is not assignable to `Template7` [bad-assignment]
+ERROR protocols_definition.py:370:22-38: `Concrete7_Bad2` is not assignable to `Template7` [bad-assignment]
 """
diff --git a/conformance/results/pyright/protocols_definition.toml b/conformance/results/pyright/protocols_definition.toml
index b8252b8f7..2b983d502 100644
--- a/conformance/results/pyright/protocols_definition.toml
+++ b/conformance/results/pyright/protocols_definition.toml
@@ -97,6 +97,12 @@ protocols_definition.py:341:22 - error: Type "Concrete6_Bad3" is not assignable
   "Concrete6_Bad3" is incompatible with protocol "Template6"
     "val1" is writable in protocol
     "val1" is not read-only in protocol (reportAssignmentType)
+protocols_definition.py:369:22 - error: Type "Concrete7_Bad1" is not assignable to declared type "Template7"
+  "Concrete7_Bad1" is incompatible with protocol "Template7"
+    "val1" is defined as a ClassVar in protocol (reportAssignmentType)
+protocols_definition.py:370:22 - error: Type "Concrete7_Bad2" is not assignable to declared type "Template7"
+  "Concrete7_Bad2" is incompatible with protocol "Template7"
+    "val1" is defined as a ClassVar in protocol (reportAssignmentType)
 """
 conformance_automated = "Pass"
 errors_diff = """
diff --git a/conformance/results/results.html b/conformance/results/results.html
index 2a8c27f44..7c89516d1 100644
--- a/conformance/results/results.html
+++ b/conformance/results/results.html
@@ -1384,7 +1384,12 @@ <h1>Python Type System Conformance Test Results</h1>
                                 <li>Does not detect protocol mismatch if concrete method's parameters are position-only.</li>
                             </ul>
                         </td>
-                        <td class="conformant">Pass</td>
+                        <td class="partially-conformant tooltip">
+                            Partial
+                            <ul class="notes">
+                                <li>Incorrectly accepts an instance-only attribute as satisfying a <code>ClassVar</code> protocol member.</li>
+                            </ul>
+                        </td>
                         <td class="conformant">Pass</td>
                         <td class="conformant">Pass</td>
                         <td class="conformant">Pass</td>
@@ -1536,7 +1541,7 @@ <h1>Python Type System Conformance Test Results</h1>
                     <tr class="summary">
                         <td></td>
                         <td>9.5 / 11 • 86.4%</td>
-                        <td>10 / 11 • 90.9%</td>
+                        <td>9.5 / 11 • 86.4%</td>
                         <td>10.5 / 11 • 95.5%</td>
                         <td>10.5 / 11 • 95.5%</td>
                         <td>6.5 / 11 • 59.1%</td>
@@ -2728,7 +2733,7 @@ <h1>Python Type System Conformance Test Results</h1>
                     <tr>
                         <td></td>
                         <td>108.5 / 145 • 74.8%</td>
-                        <td>128 / 145 • 88.3%</td>
+                        <td>127.5 / 145 • 87.9%</td>
                         <td>140.5 / 145 • 96.9%</td>
                         <td>135.5 / 145 • 93.4%</td>
                         <td>128 / 145 • 88.3%</td>
diff --git a/conformance/results/ty/protocols_definition.toml b/conformance/results/ty/protocols_definition.toml
index 29e82bd3b..09ccdd19e 100644
--- a/conformance/results/ty/protocols_definition.toml
+++ b/conformance/results/ty/protocols_definition.toml
@@ -23,4 +23,6 @@ protocols_definition.py:289:22: error[invalid-assignment] Object of type `Concre
 protocols_definition.py:339:22: error[invalid-assignment] Object of type `Concrete6_Bad1` is not assignable to `Template6`
 protocols_definition.py:340:22: error[invalid-assignment] Object of type `Concrete6_Bad2` is not assignable to `Template6`
 protocols_definition.py:341:22: error[invalid-assignment] Object of type `Concrete6_Bad3` is not assignable to `Template6`
+protocols_definition.py:369:22: error[invalid-assignment] Object of type `Concrete7_Bad1` is not assignable to `Template7`
+protocols_definition.py:370:22: error[invalid-assignment] Object of type `Concrete7_Bad2` is not assignable to `Template7`
 """
diff --git a/conformance/results/zuban/protocols_definition.toml b/conformance/results/zuban/protocols_definition.toml
index a0316e0ea..26d390b47 100644
--- a/conformance/results/zuban/protocols_definition.toml
+++ b/conformance/results/zuban/protocols_definition.toml
@@ -67,4 +67,7 @@ protocols_definition.py:340: error: Incompatible types in assignment (expression
 protocols_definition.py:340: note: Protocol member Template6.val1 expected settable variable, got read-only attribute
 protocols_definition.py:341: error: Incompatible types in assignment (expression has type "Concrete6_Bad3", variable has type "Template6")  [assignment]
 protocols_definition.py:341: note: Protocol member Template6.val1 expected settable variable, got read-only attribute
+protocols_definition.py:369: error: Incompatible types in assignment (expression has type "Concrete7_Bad1", variable has type "Template7")  [assignment]
+protocols_definition.py:369: note: Protocol member Template7.val1 expected class variable, got instance variable
+protocols_definition.py:370: error: Incompatible types in assignment (expression has type "Concrete7_Bad2", variable has type "Template7")  [assignment]
 """
diff --git a/conformance/tests/protocols_class_objects.py b/conformance/tests/protocols_class_objects.py
index 79de51204..2a498438b 100644
--- a/conformance/tests/protocols_class_objects.py
+++ b/conformance/tests/protocols_class_objects.py
@@ -105,5 +105,5 @@ class ConcreteC3(metaclass=CMeta):
 pc2: ProtoC2 = ConcreteC1  # OK
 pc3: ProtoC1 = ConcreteC2  # E
 pc4: ProtoC2 = ConcreteC2  # E
-pc5: ProtoC1 = ConcreteC3  # E
+pc5: ProtoC1 = ConcreteC3  # E?: Explicit ClassVar matching is unspecified
 pc6: ProtoC2 = ConcreteC3  # OK
diff --git a/conformance/tests/protocols_definition.py b/conformance/tests/protocols_definition.py
index bf046ee8c..7252dfc16 100644
--- a/conformance/tests/protocols_definition.py
+++ b/conformance/tests/protocols_definition.py
@@ -114,7 +114,7 @@ class Concrete2_Bad4:
 v2_bad1: Template2 = Concrete2_Bad1()  # E
 v2_bad2: Template2 = Concrete2_Bad2()  # E
 v2_bad3: Template2 = Concrete2_Bad3()  # E
-v2_bad4: Template2 = Concrete2_Bad4()  # E
+v2_bad4: Template2 = Concrete2_Bad4()  # E?: Explicit ClassVar matching is unspecified
 
 
 class Template3(Protocol):
@@ -339,3 +339,32 @@ class Concrete6_Bad3:
 v6_bad1: Template6 = Concrete6_Bad1()  # E
 v6_bad2: Template6 = Concrete6_Bad2()  # E: named tuple is immutable
 v6_bad3: Template6 = Concrete6_Bad3()  # E: dataclass is frozen
+
+
+# The specification leaves two possible interpretations of a ClassVar protocol
+# member. One interpretation requires the implementing attribute to be explicitly
+# declared with ClassVar. The other interpretation imposes only structural
+# requirements: the attribute must be readable and writable on the class object
+# and readable on instances of the class. Both interpretations therefore require
+# the following assignments to be rejected.
+
+
+class Template7(Protocol):
+    val1: ClassVar[int]
+
+
+class Concrete7_Bad1:
+    def __init__(self) -> None:
+        self.val1: int = 42
+
+
+class Concrete7Meta(type):
+    val1: int = 42
+
+
+class Concrete7_Bad2(metaclass=Concrete7Meta):
+    pass
+
+
+v7_bad1: Template7 = Concrete7_Bad1()  # E: val1 is not readable on the class object
+v7_bad2: Template7 = Concrete7_Bad2()  # E: val1 is not readable on instances