diff --git a/authenticate/handlers.go b/authenticate/handlers.go
index 5ea9c5c07..9b0aba49c 100644
--- a/authenticate/handlers.go
+++ b/authenticate/handlers.go
@@ -216,6 +216,8 @@ func (a *Authenticate) SignIn(w http.ResponseWriter, r *http.Request) error {
 		a.cfg.profileTrimFn(profile)
 	}
 
+	a.logAuthenticateEvent(r, profile)
+
 	redirectTo, err := urlutil.CallbackURL(state.hpkePrivateKey, proxyPublicKey, requestParams, profile)
 	if err != nil {
 		return httputil.NewError(http.StatusInternalServerError, err)
@@ -315,6 +317,8 @@ func (a *Authenticate) reauthenticateOrFail(w http.ResponseWriter, r *http.Reque
 		return err
 	}
 
+	a.logAuthenticateEvent(r, nil)
+
 	state.sessionStore.ClearSession(w, r)
 	redirectURL := state.redirectURL.ResolveReference(r.URL)
 	nonce := csrf.Token(r)
diff --git a/authenticate/middleware.go b/authenticate/middleware.go
index 86cc3cbdb..e7e4c95b8 100644
--- a/authenticate/middleware.go
+++ b/authenticate/middleware.go
@@ -2,10 +2,14 @@ package authenticate
 
 import (
 	"net/http"
+	"net/url"
 
 	"github.com/pomerium/pomerium/internal/httputil"
+	"github.com/pomerium/pomerium/internal/log"
 	"github.com/pomerium/pomerium/internal/middleware"
 	"github.com/pomerium/pomerium/internal/urlutil"
+	"github.com/pomerium/pomerium/pkg/grpc/identity"
+	"github.com/pomerium/pomerium/pkg/hpke"
 )
 
 // requireValidSignatureOnRedirect validates the pomerium_signature if a redirect_uri or pomerium_signature
@@ -48,3 +52,40 @@ func (a *Authenticate) getExternalRequest(r *http.Request) *http.Request {
 
 	return urlutil.GetExternalRequest(internalURL, externalURL, r)
 }
+
+func (a *Authenticate) logAuthenticateEvent(r *http.Request, profile *identity.Profile) {
+	state := a.state.Load()
+	ctx := r.Context()
+	pub, params, err := hpke.DecryptURLValues(state.hpkePrivateKey, r.Form)
+	if err != nil {
+		log.Warn(ctx).Err(err).Msg("log authenticate event: failed to decrypt request params")
+	}
+
+	evt := log.Info(ctx).
+		Str("pomerium_version", params.Get(urlutil.QueryVersion)).
+		Str("pomerium_request_uuid", params.Get(urlutil.QueryRequestUUID)).
+		Str("pomerium_pub", pub.String())
+
+	if uid := getUserID(profile); uid != "" {
+		evt = evt.Str("authenticate_event", "sign_in_completed").
+			Str("pomerium_idp_user", getUserID(profile))
+	} else {
+		evt = evt.Str("authenticate_event", "sign_in")
+	}
+
+	if redirectURL, err := url.Parse(params.Get(urlutil.QueryRedirectURI)); err == nil {
+		evt = evt.Str("domain", redirectURL.Hostname())
+	}
+
+	evt.Msg("authenticate: event")
+}
+
+func getUserID(profile *identity.Profile) string {
+	if profile == nil {
+		return ""
+	}
+	if profile.Claims == nil {
+		return ""
+	}
+	return profile.Claims.Fields["sub"].GetStringValue()
+}
diff --git a/internal/urlutil/known.go b/internal/urlutil/known.go
index e7833e098..20d1cd03d 100644
--- a/internal/urlutil/known.go
+++ b/internal/urlutil/known.go
@@ -4,8 +4,12 @@ import (
 	"fmt"
 	"net/http"
 	"net/url"
+	"os"
+	"runtime"
+	"strings"
 	"time"
 
+	"github.com/google/uuid"
 	"google.golang.org/protobuf/encoding/protojson"
 
 	"github.com/pomerium/pomerium/internal/version"
@@ -21,6 +25,15 @@ const DefaultDeviceType = "any"
 
 const signInExpiry = time.Minute * 5
 
+var (
+	pomeriumRuntime = os.Getenv("POMERIUM_RUNTIME")
+	pomeriumArch    = fmt.Sprintf("%s/%s", runtime.GOOS, runtime.GOARCH)
+)
+
+func versionStr() string {
+	return strings.Join([]string{version.FullVersion(), pomeriumArch, pomeriumRuntime}, " ")
+}
+
 // CallbackURL builds the callback URL using an HPKE encrypted query string.
 func CallbackURL(
 	authenticatePrivateKey *hpke.PrivateKey,
@@ -59,7 +72,7 @@ func CallbackURL(
 		return "", fmt.Errorf("error marshaling identity profile: %w", err)
 	}
 	callbackParams.Set(QueryIdentityProfile, string(rawProfile))
-	callbackParams.Set(QueryVersion, version.FullVersion())
+	callbackParams.Set(QueryVersion, versionStr())
 
 	BuildTimeParameters(callbackParams, signInExpiry)
 
@@ -99,7 +112,8 @@ func SignInURL(
 	q := signInURL.Query()
 	q.Set(QueryRedirectURI, redirectURL.String())
 	q.Set(QueryIdentityProviderID, idpID)
-	q.Set(QueryVersion, version.FullVersion())
+	q.Set(QueryVersion, versionStr())
+	q.Set(QueryRequestUUID, uuid.NewString())
 	BuildTimeParameters(q, signInExpiry)
 	q, err := hpke.EncryptURLValues(senderPrivateKey, authenticatePublicKey, q)
 	if err != nil {
@@ -119,7 +133,7 @@ func SignOutURL(r *http.Request, authenticateURL *url.URL, key []byte) string {
 	if redirectURI, ok := RedirectURL(r); ok {
 		q.Set(QueryRedirectURI, redirectURI)
 	}
-	q.Set(QueryVersion, version.FullVersion())
+	q.Set(QueryVersion, versionStr())
 	u.RawQuery = q.Encode()
 	return NewSignedURL(key, u).Sign().String()
 }
diff --git a/internal/urlutil/query_params.go b/internal/urlutil/query_params.go
index 15a0c850a..ac5a127bc 100644
--- a/internal/urlutil/query_params.go
+++ b/internal/urlutil/query_params.go
@@ -19,6 +19,7 @@ const (
 	QuerySessionEncrypted   = "pomerium_session_encrypted"
 	QuerySessionState       = "pomerium_session_state"
 	QueryVersion            = "pomerium_version"
+	QueryRequestUUID        = "pomerium_request_uuid"
 )
 
 // URL signature based query params used for verifying the authenticity of a URL.