diff --git a/gtsam/navigation/NavState.cpp b/gtsam/navigation/NavState.cpp
index bd2656b50..e7c2e0b55 100644
--- a/gtsam/navigation/NavState.cpp
+++ b/gtsam/navigation/NavState.cpp
@@ -101,7 +101,7 @@ NavState NavState::Expmap(const Vector9& xi, OptionalJacobian<9, 9> H) {
   Eigen::Block<const Vector9, 3, 1> v = dP(xi);
   Eigen::Block<const Vector9, 3, 1> a = dV(xi);
 
-  // NOTE(frank): mostly copy/paste from Pose3
+  // NOTE(frank): See Pose3::Expmap
   Rot3 nRb = Rot3::Expmap(n_omega_nb);
   double theta2 = n_omega_nb.dot(n_omega_nb);
   if (theta2 > std::numeric_limits<double>::epsilon()) {
@@ -126,7 +126,7 @@ Vector9 NavState::Logmap(const NavState& nTb, OptionalJacobian<9, 9> H) {
   TIE(nRb, n_p, n_v, nTb);
   Vector3 n_t = n_p.vector();
 
-  // NOTE(frank): mostly copy/paste from Pose3
+  // NOTE(frank): See Pose3::Logmap
   Vector9 xi;
   Vector3 n_omega_nb = Rot3::Logmap(nRb);
   double theta = n_omega_nb.norm();
@@ -147,7 +147,14 @@ Vector9 NavState::Logmap(const NavState& nTb, OptionalJacobian<9, 9> H) {
 }
 
 Matrix9 NavState::AdjointMap() const {
-  throw std::runtime_error("NavState::AdjointMap not implemented yet");
+  // NOTE(frank): See Pose3::AdjointMap
+  const Matrix3 nRb = R();
+  Matrix3 pAr = skewSymmetric(t()) * nRb;
+  Matrix3 vAr = skewSymmetric(v()) * nRb;
+  Matrix9 adj;
+  //     nR/bR nR/bP nR/bV nP/bR nP/bP nP/bV nV/bR nV/bP nV/bV
+  adj << nRb, Z_3x3, Z_3x3, pAr, nRb, Z_3x3, vAr, Z_3x3, nRb;
+  return adj;
 }
 
 Matrix7 NavState::wedge(const Vector9& xi) {
diff --git a/gtsam/navigation/NavState.h b/gtsam/navigation/NavState.h
index e7aab4b7c..0edac0f65 100644
--- a/gtsam/navigation/NavState.h
+++ b/gtsam/navigation/NavState.h
@@ -189,7 +189,7 @@ public:
       OptionalJacobian<9, 9> H = boost::none);
 
   /// Calculate Adjoint map, a 9x9 matrix that takes a tangent vector in the body frame, and transforms
-  /// it to a tangent vector at idenity, such that Exmap(AdjointMap()*xi) = (*this) * Exmpap(xi);
+  /// it to a tangent vector at identity, such that Exmap(AdjointMap()*xi) = (*this) * Exmpap(xi);
   Matrix9 AdjointMap() const;
 
   /// wedge creates Lie algebra element from tangent vector
diff --git a/gtsam/navigation/tests/testNavState.cpp b/gtsam/navigation/tests/testNavState.cpp
index 675fe95c0..8cf14fec4 100644
--- a/gtsam/navigation/tests/testNavState.cpp
+++ b/gtsam/navigation/tests/testNavState.cpp
@@ -81,16 +81,16 @@ TEST( NavState, Manifold ) {
   EXPECT(assert_equal((Matrix )eH, aH));
 
   // Check retract derivatives
-//  Matrix9 aH1, aH2;
-//  kState1.retract(xi, aH1, aH2);
-//  Matrix eH1 = numericalDerivative11<NavState, NavState>(
-//      boost::bind(&NavState::retract, _1, xi, boost::none, boost::none),
-//      kState1);
-//  EXPECT(assert_equal(eH1, aH1));
-//  Matrix eH2 = numericalDerivative11<NavState, Vector9>(
-//      boost::bind(&NavState::retract, kState1, _1, boost::none, boost::none),
-//      xi);
-//  EXPECT(assert_equal(eH2, aH2));
+  Matrix9 aH1, aH2;
+  kState1.retract(xi, aH1, aH2);
+  Matrix eH1 = numericalDerivative11<NavState, NavState>(
+      boost::bind(&NavState::retract, _1, xi, boost::none, boost::none),
+      kState1);
+  EXPECT(assert_equal(eH1, aH1));
+  Matrix eH2 = numericalDerivative11<NavState, Vector9>(
+      boost::bind(&NavState::retract, kState1, _1, boost::none, boost::none),
+      xi);
+  EXPECT(assert_equal(eH2, aH2));
 }
 
 /* ************************************************************************* */