diff --git a/metrics/circonus/circonus.go b/metrics/circonus/circonus.go
index 68e00ad..7ef50d4 100644
--- a/metrics/circonus/circonus.go
+++ b/metrics/circonus/circonus.go
@@ -2,6 +2,8 @@
 package circonus
 
 import (
+	"sync"
+
 	"github.com/circonus-labs/circonus-gometrics"
 
 	"github.com/go-kit/kit/metrics"
@@ -63,6 +65,8 @@
 type Gauge struct {
 	name string
 	m    *circonusgometrics.CirconusMetrics
+	val  float64
+	mtx  sync.RWMutex
 }
 
 // With implements Gauge, but is a no-op, because Circonus metrics have no
@@ -70,7 +74,21 @@
 func (g *Gauge) With(labelValues ...string) metrics.Gauge { return g }
 
 // Set implements Gauge.
-func (g *Gauge) Set(value float64) { g.m.SetGauge(g.name, value) }
+func (g *Gauge) Set(value float64) {
+	g.mtx.Lock()
+	defer g.mtx.Unlock()
+	g.val = value
+	g.m.SetGauge(g.name, value)
+}
+
+// Add implements metrics.Gauge.
+func (g *Gauge) Add(delta float64) {
+	g.mtx.Lock()
+	defer g.mtx.Unlock()
+	value := g.val + delta
+	g.val = value
+	g.m.SetGauge(g.name, value)
+}
 
 // Histogram is a Circonus implementation of a histogram metric.
 type Histogram struct {
diff --git a/metrics/discard/discard.go b/metrics/discard/discard.go
index 0bbab8f..a0d3b14 100644
--- a/metrics/discard/discard.go
+++ b/metrics/discard/discard.go
@@ -25,6 +25,9 @@
 // Set implements Gauge.
 func (g gauge) Set(value float64) {}
 
+// Add implements metrics.Gauge.
+func (g gauge) Add(delta float64) {}
+
 type histogram struct{}
 
 // NewHistogram returns a new no-op histogram.
diff --git a/metrics/dogstatsd/dogstatsd.go b/metrics/dogstatsd/dogstatsd.go
index 20a77dc..13e0b4f 100644
--- a/metrics/dogstatsd/dogstatsd.go
+++ b/metrics/dogstatsd/dogstatsd.go
@@ -72,6 +72,7 @@
 	return &Gauge{
 		name: d.prefix + name,
 		obs:  d.gauges.Observe,
+		add:  d.gauges.Add,
 	}
 }
 
@@ -244,6 +245,7 @@
 	name string
 	lvs  lv.LabelValues
 	obs  observeFunc
+	add  observeFunc
 }
 
 // With implements metrics.Gauge.
@@ -252,12 +254,18 @@
 		name: g.name,
 		lvs:  g.lvs.With(labelValues...),
 		obs:  g.obs,
+		add:  g.add,
 	}
 }
 
 // Set implements metrics.Gauge.
 func (g *Gauge) Set(value float64) {
 	g.obs(g.name, g.lvs, value)
+}
+
+// Add implements metrics.Gauge.
+func (g *Gauge) Add(delta float64) {
+	g.add(g.name, g.lvs, delta)
 }
 
 // Timing is a DogStatsD timing, or metrics.Histogram. Observations are
diff --git a/metrics/expvar/expvar.go b/metrics/expvar/expvar.go
index dcb5d62..ce6f3b8 100644
--- a/metrics/expvar/expvar.go
+++ b/metrics/expvar/expvar.go
@@ -50,6 +50,9 @@
 // Set implements Gauge.
 func (g *Gauge) Set(value float64) { g.f.Set(value) }
 
+// Add implements metrics.Gauge.
+func (g *Gauge) Add(delta float64) { g.f.Add(delta) }
+
 // Histogram implements the histogram metric with a combination of the generic
 // Histogram object and several expvar Floats, one for each of the 50th, 90th,
 // 95th, and 99th quantiles of observed values, with the quantile attached to
diff --git a/metrics/generic/generic.go b/metrics/generic/generic.go
index 2f7ae70..295b016 100644
--- a/metrics/generic/generic.go
+++ b/metrics/generic/generic.go
@@ -105,6 +105,20 @@
 	atomic.StoreUint64(&g.bits, math.Float64bits(value))
 }
 
+// Add implements metrics.Gauge.
+func (g *Gauge) Add(delta float64) {
+	for {
+		var (
+			old  = atomic.LoadUint64(&g.bits)
+			newf = math.Float64frombits(old) + delta
+			new  = math.Float64bits(newf)
+		)
+		if atomic.CompareAndSwapUint64(&g.bits, old, new) {
+			break
+		}
+	}
+}
+
 // Value returns the current value of the gauge.
 func (g *Gauge) Value() float64 {
 	return math.Float64frombits(atomic.LoadUint64(&g.bits))
diff --git a/metrics/graphite/graphite.go b/metrics/graphite/graphite.go
index 682e147..59532e4 100644
--- a/metrics/graphite/graphite.go
+++ b/metrics/graphite/graphite.go
@@ -182,6 +182,9 @@
 // Set implements gauge.
 func (g *Gauge) Set(value float64) { g.g.Set(value) }
 
+// Add implements metrics.Gauge.
+func (g *Gauge) Add(delta float64) { g.g.Add(delta) }
+
 // Histogram is a Graphite histogram metric. Observations are bucketed into
 // per-quantile gauges.
 type Histogram struct {
diff --git a/metrics/influx/example_test.go b/metrics/influx/example_test.go
index 1a5105c..7df3f38 100644
--- a/metrics/influx/example_test.go
+++ b/metrics/influx/example_test.go
@@ -44,11 +44,14 @@
 	gauge.With("error", "true").Set(1)
 	gauge.With("error", "false").Set(2)
 	gauge.Set(50)
+	gauge.With("test", "true").Set(1)
+	gauge.With("test", "true").Add(1)
 
 	client := &bufWriter{}
 	in.WriteTo(client)
 
 	expectedLines := []string{
+		`(influx_gauge,a=b,test=true value=2) [0-9]{19}`,
 		`(influx_gauge,a=b value=50) [0-9]{19}`,
 		`(influx_gauge,a=b,error=true value=1) [0-9]{19}`,
 		`(influx_gauge,a=b,error=false value=2) [0-9]{19}`,
@@ -59,6 +62,7 @@
 	}
 
 	// Output:
+	// influx_gauge,a=b,test=true value=2
 	// influx_gauge,a=b value=50
 	// influx_gauge,a=b,error=true value=1
 	// influx_gauge,a=b,error=false value=2
diff --git a/metrics/influx/influx.go b/metrics/influx/influx.go
index b9a3f66..1ea0cc5 100644
--- a/metrics/influx/influx.go
+++ b/metrics/influx/influx.go
@@ -66,6 +66,7 @@
 	return &Gauge{
 		name: name,
 		obs:  in.gauges.Observe,
+		add:  in.gauges.Add,
 	}
 }
 
@@ -220,6 +221,7 @@
 	name string
 	lvs  lv.LabelValues
 	obs  observeFunc
+	add  observeFunc
 }
 
 // With implements metrics.Gauge.
@@ -228,12 +230,18 @@
 		name: g.name,
 		lvs:  g.lvs.With(labelValues...),
 		obs:  g.obs,
+		add:  g.add,
 	}
 }
 
 // Set implements metrics.Gauge.
 func (g *Gauge) Set(value float64) {
 	g.obs(g.name, g.lvs, value)
+}
+
+// Add implements metrics.Gauge.
+func (g *Gauge) Add(delta float64) {
+	g.add(g.name, g.lvs, delta)
 }
 
 // Histogram is an Influx histrogram. Observations are aggregated into a
diff --git a/metrics/internal/lv/space.go b/metrics/internal/lv/space.go
index 6807347..672c900 100644
--- a/metrics/internal/lv/space.go
+++ b/metrics/internal/lv/space.go
@@ -19,6 +19,13 @@
 // the vector space, and appends the value to the list of observations.
 func (s *Space) Observe(name string, lvs LabelValues, value float64) {
 	s.nodeFor(name).observe(lvs, value)
+}
+
+// Add locates the time series identified by the name and label values in
+// the vector space, and appends the delta to the last value in the list of
+// observations.
+func (s *Space) Add(name string, lvs LabelValues, delta float64) {
+	s.nodeFor(name).add(lvs, delta)
 }
 
 // Walk traverses the vector space and invokes fn for each non-empty time series
@@ -91,6 +98,34 @@
 	child.observe(tail, value)
 }
 
+func (n *node) add(lvs LabelValues, delta float64) {
+	n.mtx.Lock()
+	defer n.mtx.Unlock()
+	if len(lvs) == 0 {
+		var value float64
+		if len(n.observations) > 0 {
+			value = last(n.observations) + delta
+		} else {
+			value = delta
+		}
+		n.observations = append(n.observations, value)
+		return
+	}
+	if len(lvs) < 2 {
+		panic("too few LabelValues; programmer error!")
+	}
+	head, tail := pair{lvs[0], lvs[1]}, lvs[2:]
+	if n.children == nil {
+		n.children = map[pair]*node{}
+	}
+	child, ok := n.children[head]
+	if !ok {
+		child = &node{}
+		n.children[head] = child
+	}
+	child.add(tail, delta)
+}
+
 func (n *node) walk(lvs LabelValues, fn func(LabelValues, []float64) bool) bool {
 	n.mtx.RLock()
 	defer n.mtx.RUnlock()
@@ -104,3 +139,7 @@
 	}
 	return true
 }
+
+func last(a []float64) float64 {
+	return a[len(a)-1]
+}
diff --git a/metrics/metrics.go b/metrics/metrics.go
index 719c3d8..a7ba1b1 100644
--- a/metrics/metrics.go
+++ b/metrics/metrics.go
@@ -12,6 +12,7 @@
 type Gauge interface {
 	With(labelValues ...string) Gauge
 	Set(value float64)
+	Add(delta float64)
 }
 
 // Histogram describes a metric that takes repeated observations of the same
diff --git a/metrics/multi/multi.go b/metrics/multi/multi.go
index 971dd17..0f4a9e0 100644
--- a/metrics/multi/multi.go
+++ b/metrics/multi/multi.go
@@ -54,6 +54,13 @@
 	return next
 }
 
+// Add implements metrics.Gauge.
+func (g Gauge) Add(delta float64) {
+	for _, gauge := range g {
+		gauge.Add(delta)
+	}
+}
+
 // Histogram collects multiple individual histograms and treats them as a unit.
 type Histogram []metrics.Histogram
 
diff --git a/metrics/multi/multi_test.go b/metrics/multi/multi_test.go
index b6f5cfa..bc52f9d 100644
--- a/metrics/multi/multi_test.go
+++ b/metrics/multi/multi_test.go
@@ -33,8 +33,9 @@
 	mg.Set(9)
 	mg.Set(8)
 	mg.Set(7)
+	mg.Add(3)
 
-	want := "[9 8 7]"
+	want := "[9 8 7 10]"
 	for i, m := range []fmt.Stringer{g1, g2, g3} {
 		if have := m.String(); want != have {
 			t.Errorf("g%d: want %q, have %q", i+1, want, have)
@@ -76,6 +77,15 @@
 func (g *mockGauge) Set(value float64)            { g.obs = append(g.obs, value) }
 func (g *mockGauge) With(...string) metrics.Gauge { return g }
 func (g *mockGauge) String() string               { return fmt.Sprintf("%v", g.obs) }
+func (g *mockGauge) Add(delta float64) {
+	var value float64
+	if len(g.obs) > 0 {
+		value = g.obs[len(g.obs)-1] + delta
+	} else {
+		value = delta
+	}
+	g.obs = append(g.obs, value)
+}
 
 type mockHistogram struct {
 	obs []float64
diff --git a/metrics/pcp/pcp.go b/metrics/pcp/pcp.go
index a8887a0..e4521c6 100644
--- a/metrics/pcp/pcp.go
+++ b/metrics/pcp/pcp.go
@@ -82,7 +82,7 @@
 func (g *Gauge) Set(value float64) { g.g.Set(value) }
 
 // Add adds a value to the gauge.
-func (g *Gauge) Add(value float64) { g.g.Inc(value) }
+func (g *Gauge) Add(delta float64) { g.g.Inc(delta) }
 
 // Histogram wraps a speed Histogram.
 type Histogram struct {
diff --git a/metrics/statsd/statsd.go b/metrics/statsd/statsd.go
index 6196105..8dfbf6f 100644
--- a/metrics/statsd/statsd.go
+++ b/metrics/statsd/statsd.go
@@ -74,6 +74,7 @@
 	return &Gauge{
 		name: s.prefix + name,
 		obs:  s.gauges.Observe,
+		add:  s.gauges.Add,
 	}
 }
 
@@ -201,6 +202,7 @@
 type Gauge struct {
 	name string
 	obs  observeFunc
+	add  observeFunc
 }
 
 // With is a no-op.
@@ -211,6 +213,11 @@
 // Set implements metrics.Gauge.
 func (g *Gauge) Set(value float64) {
 	g.obs(g.name, lv.LabelValues{}, value)
+}
+
+// Add implements metrics.Gauge.
+func (g *Gauge) Add(delta float64) {
+	g.add(g.name, lv.LabelValues{}, delta)
 }
 
 // Timing is a StatsD timing, or metrics.Histogram. Observations are
diff --git a/metrics/teststat/teststat.go b/metrics/teststat/teststat.go
index 991f5c0..5a1885a 100644
--- a/metrics/teststat/teststat.go
+++ b/metrics/teststat/teststat.go
@@ -42,6 +42,12 @@
 		f := float64(a[i])
 		gauge.Set(f)
 		want = f
+	}
+
+	for i := 0; i < n; i++ {
+		f := float64(a[i])
+		gauge.Add(f)
+		want += f
 	}
 
 	if have := value(); want != have {