diff --git a/extensions/functions_comparison.yaml b/extensions/functions_comparison.yaml
index dffc5728d..517f8e38f 100644
--- a/extensions/functions_comparison.yaml
+++ b/extensions/functions_comparison.yaml
@@ -147,6 +147,38 @@ scalar_functions:
             name: high
             description: The value to check if less than or equal to.
         return: boolean
+  - name: "is_true"
+    description: Whether a value is true.
+    impls:
+      - args:
+          - value: boolean?
+            name: x
+        return: BOOLEAN
+        nullability: DECLARED_OUTPUT
+  - name: "is_not_true"
+    description: Whether a value is not true.
+    impls:
+      - args:
+          - value: boolean?
+            name: x
+        return: BOOLEAN
+        nullability: DECLARED_OUTPUT
+  - name: "is_false"
+    description: Whether a value is false.
+    impls:
+      - args:
+          - value: boolean?
+            name: x
+        return: BOOLEAN
+        nullability: DECLARED_OUTPUT
+  - name: "is_not_false"
+    description: Whether a value is not false.
+    impls:
+      - args:
+          - value: boolean?
+            name: x
+        return: BOOLEAN
+        nullability: DECLARED_OUTPUT
   -
     name: "is_null"
     description: Whether a value is null. NaN is not null.
diff --git a/tests/cases/comparison/is_false.test b/tests/cases/comparison/is_false.test
new file mode 100644
index 000000000..c11295ac3
--- /dev/null
+++ b/tests/cases/comparison/is_false.test
@@ -0,0 +1,6 @@
+### SUBSTRAIT_SCALAR_TEST: v1.0
+### SUBSTRAIT_INCLUDE: '/extensions/functions_comparison.yaml'
+
+is_false(true::bool) = false::bool
+is_false(false::bool) = true::bool
+is_false(null::bool) = false::bool
diff --git a/tests/cases/comparison/is_not_false.test b/tests/cases/comparison/is_not_false.test
new file mode 100644
index 000000000..4301e041f
--- /dev/null
+++ b/tests/cases/comparison/is_not_false.test
@@ -0,0 +1,6 @@
+### SUBSTRAIT_SCALAR_TEST: v1.0
+### SUBSTRAIT_INCLUDE: '/extensions/functions_comparison.yaml'
+
+is_not_false(true::bool) = true::bool
+is_not_false(false::bool) = false::bool
+is_not_false(null::bool) = true::bool
diff --git a/tests/cases/comparison/is_not_true b/tests/cases/comparison/is_not_true
new file mode 100644
index 000000000..3dafdaee1
--- /dev/null
+++ b/tests/cases/comparison/is_not_true
@@ -0,0 +1,6 @@
+### SUBSTRAIT_SCALAR_TEST: v1.0
+### SUBSTRAIT_INCLUDE: '/extensions/functions_comparison.yaml'
+
+is_not_true(true::bool) = false::bool
+is_not_true(false::bool) = true::bool
+is_not_true(null::bool) = true::bool
diff --git a/tests/cases/comparison/is_true.test b/tests/cases/comparison/is_true.test
new file mode 100644
index 000000000..f3bb7ff0e
--- /dev/null
+++ b/tests/cases/comparison/is_true.test
@@ -0,0 +1,6 @@
+### SUBSTRAIT_SCALAR_TEST: v1.0
+### SUBSTRAIT_INCLUDE: '/extensions/functions_comparison.yaml'
+
+is_true(true::bool) = true::bool
+is_true(false::bool) = false::bool
+is_true(null::bool) = false::bool