diff --git a/build_request.go b/build_request.go
index 55cbb2a..0885c1c 100644
--- a/build_request.go
+++ b/build_request.go
@@ -46,6 +46,12 @@ func (sp *SAMLServiceProvider) buildAuthnRequest(includeSig bool) (*etree.Docume
 	authnRequest.CreateAttr("AssertionConsumerServiceURL", sp.AssertionConsumerServiceURL)
 	authnRequest.CreateAttr("IssueInstant", sp.Clock.Now().UTC().Format(issueInstantFormat))
 	authnRequest.CreateAttr("Destination", sp.IdentityProviderSSOURL)
+	if sp.ForceAuthn {
+		authnRequest.CreateAttr("ForceAuthn", "true")
+	}
+	if sp.IsPassive {
+		authnRequest.CreateAttr("IsPassive", "true")
+	}
 
 	// NOTE(russell_h): In earlier versions we mistakenly sent the IdentityProviderIssuer
 	// in the AuthnRequest. For backwards compatibility we will fall back to that
diff --git a/build_request_test.go b/build_request_test.go
index 3930a72..dbb43de 100644
--- a/build_request_test.go
+++ b/build_request_test.go
@@ -129,3 +129,87 @@ func TestRequestedAuthnContextIncluded(t *testing.T) {
 	require.Equal(t, el.Tag, "AuthnContextClassRef")
 	require.Equal(t, el.Text(), AuthnContextPasswordProtectedTransport)
 }
+
+func TestForceAuthnOmitted(t *testing.T) {
+	spURL := "https://sp.test"
+	sp := SAMLServiceProvider{
+		AssertionConsumerServiceURL: spURL,
+		AudienceURI:                 spURL,
+		IdentityProviderIssuer:      spURL,
+		IdentityProviderSSOURL:      "https://idp.test/saml/sso",
+	}
+
+	request, err := sp.BuildAuthRequest()
+	require.NoError(t, err)
+
+	doc := etree.NewDocument()
+	err = doc.ReadFromString(request)
+	require.NoError(t, err)
+
+	attr := doc.Root().SelectAttr("ForceAuthn")
+	require.Nil(t, attr)
+}
+
+func TestForceAuthnIncluded(t *testing.T) {
+	spURL := "https://sp.test"
+	sp := SAMLServiceProvider{
+		AssertionConsumerServiceURL: spURL,
+		AudienceURI:                 spURL,
+		IdentityProviderIssuer:      spURL,
+		IdentityProviderSSOURL:      "https://idp.test/saml/sso",
+		ForceAuthn:                  true,
+	}
+
+	request, err := sp.BuildAuthRequest()
+	require.NoError(t, err)
+
+	doc := etree.NewDocument()
+	err = doc.ReadFromString(request)
+	require.NoError(t, err)
+
+	attr := doc.Root().SelectAttr("ForceAuthn")
+	require.NotNil(t, attr)
+	require.Equal(t, "true", attr.Value)
+}
+
+func TestIsPassiveOmitted(t *testing.T) {
+	spURL := "https://sp.test"
+	sp := SAMLServiceProvider{
+		AssertionConsumerServiceURL: spURL,
+		AudienceURI:                 spURL,
+		IdentityProviderIssuer:      spURL,
+		IdentityProviderSSOURL:      "https://idp.test/saml/sso",
+	}
+
+	request, err := sp.BuildAuthRequest()
+	require.NoError(t, err)
+
+	doc := etree.NewDocument()
+	err = doc.ReadFromString(request)
+	require.NoError(t, err)
+
+	attr := doc.Root().SelectAttr("IsPassive")
+	require.Nil(t, attr)
+}
+
+func TestIsPassiveIncluded(t *testing.T) {
+	spURL := "https://sp.test"
+	sp := SAMLServiceProvider{
+		AssertionConsumerServiceURL: spURL,
+		AudienceURI:                 spURL,
+		IdentityProviderIssuer:      spURL,
+		IdentityProviderSSOURL:      "https://idp.test/saml/sso",
+		IsPassive:                   true,
+	}
+
+	request, err := sp.BuildAuthRequest()
+	require.NoError(t, err)
+
+	doc := etree.NewDocument()
+	err = doc.ReadFromString(request)
+	require.NoError(t, err)
+
+	attr := doc.Root().SelectAttr("IsPassive")
+	require.NotNil(t, attr)
+	require.Equal(t, "true", attr.Value)
+}
diff --git a/saml.go b/saml.go
index 88ef8ae..c603132 100644
--- a/saml.go
+++ b/saml.go
@@ -51,6 +51,15 @@ type SAMLServiceProvider struct {
 	SignAuthnRequestsAlgorithm     string
 	SignAuthnRequestsCanonicalizer dsig.Canonicalizer
 
+	// ForceAuthn attribute in authentication request forces the identity provider to
+	// re-authenticate the presenter directly rather than rely on a previous security context.
+	// NOTE: If both ForceAuthn and IsPassive are "true", the identity provider MUST NOT freshly
+	// authenticate the presenter unless the constraints of IsPassive can be met.
+	ForceAuthn bool
+	// IsPassive attribute in authentication request requires that the identity provider and the
+	// user agent itself MUST NOT visibly take control of the user interface from the requester
+	// and interact with the presenter in a noticeable fashion.
+	IsPassive bool
 	// RequestedAuthnContext allows service providers to require that the identity
 	// provider use specific authentication mechanisms. Leaving this unset will
 	// permit the identity provider to choose the auth method. To maximize compatibility