diff --git a/internal/monitor/monitor.go b/internal/monitor/monitor.go
index 76a55bb..1bb02fe 100644
--- a/internal/monitor/monitor.go
+++ b/internal/monitor/monitor.go
@@ -243,7 +243,7 @@ func checkByID(id int) {
 	case "dns":
 		checkDNS(site)
 	case "group":
-		// groups don't perform checks
+		checkGroup(site)
 	}
 }
 
@@ -437,6 +437,44 @@ func checkPort(site models.Site) {
 	handleStatusChange(updatedSite, "UP", 0, latency)
 }
 
+func checkGroup(site models.Site) {
+	Mutex.RLock()
+	status := "UP"
+	hasChildren := false
+	allPaused := true
+	for _, child := range LiveState {
+		if child.ParentID != site.ID || child.Type == "group" {
+			continue
+		}
+		hasChildren = true
+		if !child.Paused {
+			allPaused = false
+		}
+		if child.Paused {
+			continue
+		}
+		if child.Status == "DOWN" || child.Status == "SSL EXP" {
+			status = "DOWN"
+		} else if child.Status == "PENDING" && status != "DOWN" {
+			status = "PENDING"
+		}
+	}
+	Mutex.RUnlock()
+
+	if !hasChildren {
+		status = "PENDING"
+	}
+
+	Mutex.Lock()
+	s := LiveState[site.ID]
+	s.Status = status
+	if hasChildren && allPaused {
+		s.Paused = true
+	}
+	LiveState[site.ID] = s
+	Mutex.Unlock()
+}
+
 func checkDNS(site models.Site) {
 	host := site.Hostname
 	if host == "" {
diff --git a/internal/tui/tab_sites.go b/internal/tui/tab_sites.go
index fecd183..3a590a0 100644
--- a/internal/tui/tab_sites.go
+++ b/internal/tui/tab_sites.go
@@ -34,6 +34,11 @@ var (
 
 	siteBorderStyle = lipgloss.NewStyle().
 			Foreground(lipgloss.Color("#444"))
+
+	siteGroupStyle = lipgloss.NewStyle().
+			Padding(0, 1).
+			Bold(true).
+			Foreground(lipgloss.Color("#7D56F4"))
 )
 
 type siteFormData struct {
@@ -50,6 +55,7 @@ type siteFormData struct {
 	Timeout     string
 	Description string
 	IgnoreTLS   bool
+	GroupID     string
 }
 
 func latencySparkline(latencies []time.Duration, width int) string {
@@ -222,10 +228,42 @@ func (m Model) viewSitesTab() string {
 	selectedVisual := m.cursor - m.tableOffset
 
 	var rows [][]string
+	var groupRows []int
 	for i := m.tableOffset; i < end; i++ {
 		site := m.sites[i]
-		hist, _ := monitor.GetHistory(site.ID)
 
+		if site.Type == "group" {
+			groupRows = append(groupRows, i-m.tableOffset)
+			arrow := "▾"
+			if m.collapsed[site.ID] {
+				arrow = "▸"
+			}
+			rows = append(rows, []string{
+				strconv.Itoa(i + 1),
+				m.zones.Mark(fmt.Sprintf("site-%d", i), arrow+" "+limitStr(site.Name, 11)),
+				"group",
+				fmtStatus(site.Status, site.Paused),
+				subtleStyle.Render("—"),
+				subtleStyle.Render("—"),
+				subtleStyle.Render(strings.Repeat("·", sparkWidth)),
+				subtleStyle.Render("-"),
+				subtleStyle.Render("—"),
+			})
+			continue
+		}
+
+		name := site.Name
+		if site.ParentID > 0 {
+			prefix := "├"
+			if i+1 >= len(m.sites) || m.sites[i+1].ParentID != site.ParentID {
+				prefix = "└"
+			}
+			name = prefix + " " + limitStr(name, 11)
+		} else {
+			name = limitStr(name, 13)
+		}
+
+		hist, _ := monitor.GetHistory(site.ID)
 		var spark string
 		if site.Type == "push" {
 			spark = heartbeatSparkline(hist.Statuses, sparkWidth)
@@ -235,7 +273,7 @@ func (m Model) viewSitesTab() string {
 
 		rows = append(rows, []string{
 			strconv.Itoa(i + 1),
-			m.zones.Mark(fmt.Sprintf("site-%d", i), limitStr(site.Name, 13)),
+			m.zones.Mark(fmt.Sprintf("site-%d", i), name),
 			site.Type,
 			fmtStatus(site.Status, site.Paused),
 			fmtLatency(site.Latency),
@@ -246,6 +284,15 @@ func (m Model) viewSitesTab() string {
 		})
 	}
 
+	isGroupRow := func(row int) bool {
+		for _, g := range groupRows {
+			if g == row {
+				return true
+			}
+		}
+		return false
+	}
+
 	tableWidth := m.termWidth - 6
 	if tableWidth < 40 {
 		tableWidth = 40
@@ -264,6 +311,9 @@ func (m Model) viewSitesTab() string {
 			if row == selectedVisual {
 				return siteSelectedStyle
 			}
+			if isGroupRow(row) {
+				return siteGroupStyle
+			}
 			return siteCellStyle
 		})
 
@@ -278,6 +328,7 @@ func (m *Model) initSiteHuhForm() tea.Cmd {
 		Retries:   "0",
 		Timeout:   "5",
 		Port:      "0",
+		GroupID:   "0",
 	}
 
 	if m.editID > 0 {
@@ -296,6 +347,7 @@ func (m *Model) initSiteHuhForm() tea.Cmd {
 				m.siteFormData.Timeout = strconv.Itoa(site.Timeout)
 				m.siteFormData.Description = site.Description
 				m.siteFormData.IgnoreTLS = site.IgnoreTLS
+				m.siteFormData.GroupID = strconv.Itoa(site.ParentID)
 				break
 			}
 		}
@@ -311,6 +363,13 @@ func (m *Model) initSiteHuhForm() tea.Cmd {
 		}
 	}
 
+	groupOpts := []huh.Option[string]{huh.NewOption("None", "0")}
+	for _, s := range m.sites {
+		if s.Type == "group" && s.ID != m.editID {
+			groupOpts = append(groupOpts, huh.NewOption(s.Name, strconv.Itoa(s.ID)))
+		}
+	}
+
 	m.huhForm = huh.NewForm(
 		huh.NewGroup(
 			huh.NewInput().Title("Monitor Name").
@@ -331,12 +390,17 @@ func (m *Model) initSiteHuhForm() tea.Cmd {
 					huh.NewOption("DNS", "dns"),
 					huh.NewOption("Group", "group"),
 				).Value(&m.siteFormData.SiteType),
+			huh.NewSelect[string]().Title("Alert Channel").
+				Options(alertOpts...).
+				Value(&m.siteFormData.AlertID),
+		).Title("Monitor Settings"),
+		huh.NewGroup(
 			huh.NewInput().Title("URL").
 				Placeholder("https://example.com").
 				Description("Required for HTTP monitors").
 				Value(&m.siteFormData.URL).
 				Validate(func(s string) error {
-					if m.siteFormData.SiteType == "push" {
+					if m.siteFormData.SiteType == "push" || m.siteFormData.SiteType == "group" {
 						return nil
 					}
 					if s == "" {
@@ -358,6 +422,9 @@ func (m *Model) initSiteHuhForm() tea.Cmd {
 				Placeholder("60").
 				Value(&m.siteFormData.Interval).
 				Validate(func(s string) error {
+					if m.siteFormData.SiteType == "group" {
+						return nil
+					}
 					v, err := strconv.Atoi(s)
 					if err != nil {
 						return fmt.Errorf("must be a number")
@@ -367,11 +434,9 @@ func (m *Model) initSiteHuhForm() tea.Cmd {
 					}
 					return nil
 				}),
-			huh.NewSelect[string]().Title("Alert Channel").
-				Options(alertOpts...).
-				Value(&m.siteFormData.AlertID),
-		).Title("Monitor Settings"),
-		huh.NewGroup(
+			huh.NewSelect[string]().Title("Parent Group").
+				Options(groupOpts...).
+				Value(&m.siteFormData.GroupID),
 			huh.NewInput().Title("Hostname / IP").
 				Placeholder("10.0.0.1").
 				Description("Target for ping/port/DNS monitors").
@@ -394,6 +459,9 @@ func (m *Model) initSiteHuhForm() tea.Cmd {
 				Placeholder("5").
 				Value(&m.siteFormData.Timeout).
 				Validate(func(s string) error {
+					if m.siteFormData.SiteType == "group" {
+						return nil
+					}
 					v, err := strconv.Atoi(s)
 					if err != nil {
 						return fmt.Errorf("must be a number")
@@ -406,7 +474,9 @@ func (m *Model) initSiteHuhForm() tea.Cmd {
 			huh.NewInput().Title("Description").
 				Placeholder("Optional description").
 				Value(&m.siteFormData.Description),
-		).Title("Connection"),
+		).Title("Connection").WithHideFunc(func() bool {
+			return m.siteFormData.SiteType == "group"
+		}),
 		huh.NewGroup(
 			huh.NewConfirm().Title("Monitor SSL Certificate?").
 				Value(&m.siteFormData.CheckSSL),
@@ -438,7 +508,9 @@ func (m *Model) initSiteHuhForm() tea.Cmd {
 				}),
 			huh.NewConfirm().Title("Ignore TLS Errors?").
 				Value(&m.siteFormData.IgnoreTLS),
-		).Title("Advanced"),
+		).Title("Advanced").WithHideFunc(func() bool {
+			return m.siteFormData.SiteType == "group"
+		}),
 	).WithTheme(huh.ThemeDracula())
 
 	return m.huhForm.Init()
@@ -452,6 +524,7 @@ func (m *Model) submitSiteForm() {
 	retries, _ := strconv.Atoi(d.Retries)
 	port, _ := strconv.Atoi(d.Port)
 	timeout, _ := strconv.Atoi(d.Timeout)
+	groupID, _ := strconv.Atoi(d.GroupID)
 	if interval < 1 {
 		interval = 60
 	}
@@ -474,6 +547,7 @@ func (m *Model) submitSiteForm() {
 		Timeout:         timeout,
 		Description:     d.Description,
 		IgnoreTLS:       d.IgnoreTLS,
+		ParentID:        groupID,
 	}
 
 	if m.editID > 0 {
diff --git a/internal/tui/tui.go b/internal/tui/tui.go
index 174d5c8..4972a3a 100644
--- a/internal/tui/tui.go
+++ b/internal/tui/tui.go
@@ -67,6 +67,8 @@ type Model struct {
 	deleteName string
 	deleteTab  int
 
+	collapsed map[int]bool
+
 	// harmonica animation state
 	pulseSpring harmonica.Spring
 	pulsePos    float64
@@ -90,6 +92,7 @@ func InitialModel(isAdmin bool) Model {
 		isAdmin:      isAdmin,
 		zones:        z,
 		pulseSpring:  spring,
+		collapsed:    make(map[int]bool),
 	}
 }
 
@@ -299,6 +302,12 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 					m.state = stateFormUser
 					return m, m.initUserHuhForm()
 				}
+			case " ":
+				if m.currentTab == 0 && len(m.sites) > 0 && m.sites[m.cursor].Type == "group" {
+					gid := m.sites[m.cursor].ID
+					m.collapsed[gid] = !m.collapsed[gid]
+					m.refreshData()
+				}
 			case "p":
 				if m.currentTab == 0 && len(m.sites) > 0 {
 					site := m.sites[m.cursor]
@@ -421,13 +430,40 @@ func (m *Model) adjustCursor(newLen int) {
 
 func (m *Model) refreshData() {
 	monitor.Mutex.RLock()
-	var sites []models.Site
+	var allSites []models.Site
 	for _, s := range monitor.LiveState {
-		sites = append(sites, s)
+		allSites = append(allSites, s)
 	}
 	monitor.Mutex.RUnlock()
-	sort.Slice(sites, func(i, j int) bool { return sites[i].ID < sites[j].ID })
-	m.sites = sites
+
+	var groups, ungrouped []models.Site
+	children := make(map[int][]models.Site)
+	for _, s := range allSites {
+		if s.Type == "group" {
+			groups = append(groups, s)
+		} else if s.ParentID > 0 {
+			children[s.ParentID] = append(children[s.ParentID], s)
+		} else {
+			ungrouped = append(ungrouped, s)
+		}
+	}
+	sort.Slice(groups, func(i, j int) bool { return groups[i].ID < groups[j].ID })
+	for pid := range children {
+		c := children[pid]
+		sort.Slice(c, func(i, j int) bool { return c[i].ID < c[j].ID })
+		children[pid] = c
+	}
+	sort.Slice(ungrouped, func(i, j int) bool { return ungrouped[i].ID < ungrouped[j].ID })
+
+	var ordered []models.Site
+	for _, g := range groups {
+		ordered = append(ordered, g)
+		if !m.collapsed[g.ID] {
+			ordered = append(ordered, children[g.ID]...)
+		}
+	}
+	ordered = append(ordered, ungrouped...)
+	m.sites = ordered
 	if store.Get() != nil {
 		m.alerts = store.Get().GetAllAlerts()
 		if m.isAdmin {
@@ -543,7 +579,7 @@ func (m Model) viewDashboard() string {
 		}
 	}
 
-	footer := subtleStyle.Render("\n[n] New  [e/Enter] Edit  [d] Delete  [p] Pause  [Tab/Click] Switch  [Ctrl+L] Clear  [q] Quit")
+	footer := subtleStyle.Render("\n[n] New  [e/Enter] Edit  [d] Delete  [p] Pause  [Space] Collapse  [Tab/Click] Switch  [q] Quit")
 	if m.currentTab == 3 {
 		footer = subtleStyle.Render("\n[n] Add User  [d] Revoke  [Tab/Click] Switch  [Ctrl+L] Clear  [q] Quit")
 	}