diff --git a/pkg/config/config.go b/pkg/config/config.go
index 738fc7c..5590afd 100644
--- a/pkg/config/config.go
+++ b/pkg/config/config.go
@@ -50,6 +50,8 @@ type Config struct {
 	VIP VIP
 
 	MessageFilters []*MessageFilter
+
+	Logging Logging
 }
 
 type TurnConfig struct {
@@ -99,6 +101,14 @@ type WebhookURL struct {
 	URL     string
 }
 
+// Logging configs to monitor channels or usernames.
+type Logging struct {
+	Enabled   bool
+	Directory string
+	Channels  []string
+	Usernames []string
+}
+
 // Current loaded configuration.
 var Current = DefaultConfig()
 
@@ -175,6 +185,11 @@ func DefaultConfig() Config {
 				ChatServerResponse: "Watch your language.",
 			},
 		},
+		Logging: Logging{
+			Directory: "./logs",
+			Channels:  []string{"lobby", "offtopic"},
+			Usernames: []string{},
+		},
 	}
 	c.JWT.Strict = true
 	return c
diff --git a/pkg/handlers.go b/pkg/handlers.go
index e4bf0d1..29757f0 100644
--- a/pkg/handlers.go
+++ b/pkg/handlers.go
@@ -220,12 +220,26 @@ func (s *Server) OnMessage(sub *Subscriber, msg messages.Message) {
 			return
 		}
 
+		// Log this conversation?
+		if IsLoggingUsername(sub) {
+			// The sender of this message is being logged.
+			LogMessage(sub, rcpt.Username, sub.Username, msg)
+		} else if IsLoggingUsername(rcpt) {
+			// The recipient of this message is being logged.
+			LogMessage(rcpt, sub.Username, sub.Username, msg)
+		}
+
 		if err := s.SendTo(msg.Channel, message); err != nil {
 			sub.ChatServer("Your message could not be delivered: %s", err)
 		}
 		return
 	}
 
+	// Are we logging this public channel?
+	if IsLoggingChannel(msg.Channel) {
+		LogChannel(s, msg.Channel, sub.Username, msg)
+	}
+
 	// Broadcast a chat message to the room.
 	s.Broadcast(message)
 }
diff --git a/pkg/logging.go b/pkg/logging.go
new file mode 100644
index 0000000..fbd1252
--- /dev/null
+++ b/pkg/logging.go
@@ -0,0 +1,144 @@
+package barertc
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+	"time"
+
+	"git.kirsle.net/apps/barertc/pkg/config"
+	"git.kirsle.net/apps/barertc/pkg/log"
+	"git.kirsle.net/apps/barertc/pkg/messages"
+)
+
+// IsLoggingUsername checks whether the app is currently configured to log a user's DMs.
+func IsLoggingUsername(sub *Subscriber) bool {
+	if !config.Current.Logging.Enabled {
+		return false
+	}
+
+	// Has a cached setting and writer.
+	if sub.log {
+		return true
+	}
+
+	// Check the server config.
+	for _, username := range config.Current.Logging.Usernames {
+		if username == sub.Username {
+			sub.log = true
+		}
+	}
+
+	return sub.log
+}
+
+// IsLoggingChannel checks whether the app is currently logging a public channel.
+func IsLoggingChannel(channel string) bool {
+	if !config.Current.Logging.Enabled {
+		return false
+	}
+
+	for _, value := range config.Current.Logging.Channels {
+		if value == channel {
+			return true
+		}
+	}
+	return false
+}
+
+// LogMessage appends to a user's conversation log.
+func LogMessage(sub *Subscriber, otherUsername, senderUsername string, msg messages.Message) {
+	if !sub.log {
+		return
+	}
+
+	// Create or get the filehandle.
+	fh, err := initLogFile(sub, "@"+sub.Username, otherUsername)
+	if err != nil {
+		log.Error("LogMessage(%s): %s", sub.Username, err)
+		return
+	}
+
+	fh.Write(
+		[]byte(fmt.Sprintf(
+			"%s [%s] %s\n",
+			time.Now().Format(time.RFC3339),
+			senderUsername,
+			msg.Message,
+		)),
+	)
+}
+
+// LogChannel appends to a channel's conversation log.
+func LogChannel(s *Server, channel string, username string, msg messages.Message) {
+	fh, err := initLogFile(s, channel)
+	if err != nil {
+		log.Error("LogChannel(%s): %s", channel, err)
+	}
+
+	fh.Write(
+		[]byte(fmt.Sprintf(
+			"%s [%s] %s\n",
+			time.Now().Format(time.RFC3339),
+			username,
+			msg.Message,
+		)),
+	)
+}
+
+// Initialize a logging directory.
+func initLogFile(sub LogCacheable, components ...string) (io.Writer, error) {
+	// Initialize the logfh cache?
+	var logfh = sub.GetLogFilehandleCache()
+
+	var (
+		suffix = components[len(components)-1]
+		middle = components[:len(components)-1]
+		paths  = append([]string{
+			config.Current.Logging.Directory,
+		}, middle...,
+		)
+		filename = strings.Join(
+			append(paths, suffix+".txt"),
+			"/",
+		)
+	)
+
+	// Already have this conversation log open?
+	if fh, ok := logfh[suffix]; ok {
+		return fh, nil
+	}
+
+	log.Warn("Initialize log directory: path=%+v suffix=%s", paths, suffix)
+	if err := os.MkdirAll(strings.Join(paths, "/"), 0755); err != nil {
+		return nil, err
+	}
+
+	fh, err := os.OpenFile(filename, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		return nil, err
+	}
+
+	logfh[suffix] = fh
+	return logfh[suffix], nil
+}
+
+// Interface for objects that hold log filehandle caches.
+type LogCacheable interface {
+	GetLogFilehandleCache() map[string]io.Writer
+}
+
+// Implementations of LogCacheable.
+func (sub *Subscriber) GetLogFilehandleCache() map[string]io.Writer {
+	if sub.logfh == nil {
+		sub.logfh = map[string]io.Writer{}
+	}
+	return sub.logfh
+}
+func (s *Server) GetLogFilehandleCache() map[string]io.Writer {
+	if s.logfh == nil {
+		s.logfh = map[string]io.Writer{}
+	}
+	return s.logfh
+}
diff --git a/pkg/server.go b/pkg/server.go
index 938a7de..0dfaf64 100644
--- a/pkg/server.go
+++ b/pkg/server.go
@@ -1,6 +1,7 @@
 package barertc
 
 import (
+	"io"
 	"net/http"
 	"sync"
 )
@@ -16,6 +17,9 @@ type Server struct {
 	// Connected WebSocket subscribers.
 	subscribersMu sync.RWMutex
 	subscribers   map[*Subscriber]struct{}
+
+	// Cached filehandles for channel logging.
+	logfh map[string]io.Writer
 }
 
 // NewServer initializes the Server.
diff --git a/pkg/websocket.go b/pkg/websocket.go
index 211f235..424a782 100644
--- a/pkg/websocket.go
+++ b/pkg/websocket.go
@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
 	"net/http"
 	"sort"
 	"strings"
@@ -44,6 +45,10 @@ type Subscriber struct {
 	// Record which message IDs belong to this user.
 	midMu      sync.Mutex
 	messageIDs map[int64]struct{}
+
+	// Logging.
+	log   bool
+	logfh map[string]io.Writer
 }
 
 // ReadLoop spawns a goroutine that reads from the websocket connection.