diff --git a/fig.go b/fig.go
index 510a4f4..f6590c5 100644
--- a/fig.go
+++ b/fig.go
@@ -10,6 +10,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/imdario/mergo"
 	"github.com/mitchellh/mapstructure"
 	"github.com/pelletier/go-toml"
 	"gopkg.in/yaml.v2"
@@ -76,6 +77,8 @@ type fig struct {
 	timeLayout string
 	useEnv     bool
 	envPrefix  string
+	useProfile bool
+	profile    string
 }
 
 func (f *fig) Load(cfg interface{}) error {
@@ -93,6 +96,22 @@ func (f *fig) Load(cfg interface{}) error {
 		return err
 	}
 
+	if f.useProfile {
+		profileFile, err := f.findProfileCfgFile()
+		if err != nil {
+			return err
+		}
+
+		profileVals, err := f.decodeFile(profileFile)
+		if err != nil {
+			return err
+		}
+
+		if err := mergo.Merge(&vals, profileVals, mergo.WithOverride); err != nil {
+			return err
+		}
+	}
+
 	if err := f.decodeMap(vals, cfg); err != nil {
 		return err
 	}
@@ -100,6 +119,18 @@ func (f *fig) Load(cfg interface{}) error {
 	return f.processCfg(cfg)
 }
 
+func (f *fig) findProfileCfgFile() (path string, err error) {
+	parts := strings.Split(f.filename, ".")
+	profileFileName := fmt.Sprintf("%s.%s.%s", parts[0], f.profile, parts[1])
+	for _, dir := range f.dirs {
+		path = filepath.Join(dir, profileFileName)
+		if fileExists(path) {
+			return
+		}
+	}
+	return "", fmt.Errorf("%s: %w", profileFileName, ErrFileNotFound)
+}
+
 func (f *fig) findCfgFile() (path string, err error) {
 	for _, dir := range f.dirs {
 		path = filepath.Join(dir, f.filename)
@@ -151,6 +182,7 @@ func (f *fig) decodeMap(m map[string]interface{}, result interface{}) error {
 		Result:           result,
 		TagName:          f.tag,
 		DecodeHook: mapstructure.ComposeDecodeHookFunc(
+			fromEnvironmentHookFunc(),
 			mapstructure.StringToTimeDurationHookFunc(),
 			mapstructure.StringToTimeHookFunc(f.timeLayout),
 		),
@@ -161,6 +193,31 @@ func (f *fig) decodeMap(m map[string]interface{}, result interface{}) error {
 	return dec.Decode(m)
 }
 
+func fromEnvironmentHookFunc() mapstructure.DecodeHookFunc {
+	return func(
+		f reflect.Type,
+		t reflect.Type,
+		data interface{}) (interface{}, error) {
+		if f.Kind() != reflect.String {
+			return data, nil
+		}
+
+		str := data.(string)
+		if !strings.HasPrefix(str, "${") || !strings.HasSuffix(str, "}") {
+			return data, nil
+		}
+
+		kv := str[2 : len(str)-1]
+		s := strings.Split(kv, ":")
+		envName, defaultVal := s[0], s[1]
+		if envValue, ok := os.LookupEnv(envName); ok {
+			return envValue, nil
+		} else {
+			return defaultVal, nil
+		}
+	}
+}
+
 // processCfg processes a cfg struct after it has been loaded from
 // the config file, by validating required fields and setting defaults
 // where applicable.
diff --git a/fig_test.go b/fig_test.go
index 35c3826..b67abd7 100644
--- a/fig_test.go
+++ b/fig_test.go
@@ -154,6 +154,26 @@ func Test_fig_Load(t *testing.T) {
 	}
 }
 
+func Test_fig_Load_If_Env_Set_In_Conf_File(t *testing.T) {
+	os.Setenv("POD_NAME", "ehcache")
+	for _, f := range []string{"pod.yaml", "pod.json", "pod.toml"} {
+		t.Run(f, func(t *testing.T) {
+			var cfg Pod
+			err := Load(&cfg, File(f), Dirs(filepath.Join("testdata", "valid")))
+			if err != nil {
+				t.Fatalf("unexpected err: %v", err)
+			}
+
+			want := validPodConfig()
+			want.Metadata.Name = "ehcache"
+
+			if !reflect.DeepEqual(want, cfg) {
+				t.Errorf("\nwant %+v\ngot %+v", want, cfg)
+			}
+		})
+	}
+}
+
 func Test_fig_Load_FileNotFound(t *testing.T) {
 	fig := defaultFig()
 	fig.filename = "abrakadabra"
@@ -402,6 +422,55 @@ func Test_fig_Load_WithOptions(t *testing.T) {
 	}
 }
 
+func Test_fig_Load_Server_If_Env_Set_In_Conf_File(t *testing.T) {
+	os.Setenv("SERVICE_HOST", "192.168.0.128")
+	for _, f := range []string{"server.yaml", "server.json", "server.toml"} {
+		t.Run(f, func(t *testing.T) {
+			type Server struct {
+				Host string `fig:"host"`
+			}
+
+			var cfg Server
+			err := Load(&cfg, File(f), Dirs(filepath.Join("testdata", "valid")))
+			if err != nil {
+				t.Fatalf("expected err")
+			}
+
+			want := Server{Host: "192.168.0.128"}
+
+			if !reflect.DeepEqual(want, cfg) {
+				t.Errorf("\nwant %+v\ngot %+v", want, cfg)
+			}
+		})
+	}
+}
+
+func Test_fig_Load_Server_Profile(t *testing.T) {
+	for _, f := range []string{"server.yaml", "server.json", "server.toml"} {
+		t.Run(f, func(t *testing.T) {
+			type Server struct {
+				Host   string `fig:"host"`
+				Logger struct {
+					LogLevel string `fig:"log_level" default:"info"`
+				}
+			}
+
+			var cfg Server
+			err := Load(&cfg, File(f), Dirs(filepath.Join("testdata", "valid")), UseProfile("test"))
+			if err != nil {
+				t.Fatalf("expected err %v", err)
+			}
+
+			want := Server{Host: "192.168.0.256"}
+			want.Logger.LogLevel = "debug"
+
+			if !reflect.DeepEqual(want, cfg) {
+				t.Errorf("\nwant %+v\ngot %+v", want, cfg)
+			}
+		})
+	}
+}
+
 func Test_fig_findCfgFile(t *testing.T) {
 	t.Run("finds existing file", func(t *testing.T) {
 		fig := defaultFig()
diff --git a/go.mod b/go.mod
index 5cff629..e939ae3 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,8 @@ module github.com/kkyr/fig
 go 1.14
 
 require (
+	github.com/imdario/mergo v0.3.12
 	github.com/mitchellh/mapstructure v1.1.2
 	github.com/pelletier/go-toml v1.6.0
-	gopkg.in/yaml.v2 v2.2.7
+	gopkg.in/yaml.v2 v2.3.0
 )
diff --git a/go.sum b/go.sum
index 34d6acb..6d458fa 100644
--- a/go.sum
+++ b/go.sum
@@ -2,6 +2,8 @@ github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/imdario/mergo v0.3.12 h1:b6R2BslTbIEToALKP7LxUvijTsNI9TAe80pLWN2g/HU=
+github.com/imdario/mergo v0.3.12/go.mod h1:jmQim1M+e3UYxmgPu/WyfjB3N3VflVyUjjjwH0dnCYA=
 github.com/mitchellh/mapstructure v1.1.2 h1:fmNYVwqnSfB9mZU6OS2O6GsXM+wcskZDuKQzvN1EDeE=
 github.com/mitchellh/mapstructure v1.1.2/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
 github.com/pelletier/go-toml v1.6.0 h1:aetoXYr0Tv7xRU/V4B4IZJ2QcbtMUFoNb3ORp7TzIK4=
@@ -11,3 +13,5 @@ gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/yaml.v2 v2.2.4/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.7 h1:VUgggvou5XRW9mHwD/yXxIYSMtY0zoKQf/v226p2nyo=
 gopkg.in/yaml.v2 v2.2.7/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.3.0 h1:clyUAQHOM3G0M3f5vQj7LuJrETvjVot3Z5el9nffUtU=
+gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
diff --git a/option.go b/option.go
index 0adbbf2..5551e3b 100644
--- a/option.go
+++ b/option.go
@@ -94,3 +94,16 @@ func UseEnv(prefix string) Option {
 		f.envPrefix = prefix
 	}
 }
+
+// Tag returns an option that configures the tag key that fig uses
+// when for the alt name struct tag key in fields.
+//
+//  fig.Load(&cfg, fig.UseProfile("test"))
+//
+// If this option is not used then fig uses the tag `fig`.
+func UseProfile(profile string) Option {
+	return func(f *fig) {
+		f.useProfile = true
+		f.profile = profile
+	}
+}
diff --git a/testdata/valid/pod.json b/testdata/valid/pod.json
index eeafa74..57edeab 100644
--- a/testdata/valid/pod.json
+++ b/testdata/valid/pod.json
@@ -2,7 +2,7 @@
 	"apiVersion": null,
 	"kind": "Pod",
 	"metadata": {
-		"name": "redis",
+		"name": "${POD_NAME:redis}",
 		"master": true
 	},
 	"spec": {
diff --git a/testdata/valid/pod.toml b/testdata/valid/pod.toml
index dd7b9a2..c82cf05 100644
--- a/testdata/valid/pod.toml
+++ b/testdata/valid/pod.toml
@@ -1,7 +1,7 @@
 kind = "Pod"
 
 [metadata]
-name = "redis"
+name = "${POD_NAME:redis}"
 master = true
 
 [spec]
diff --git a/testdata/valid/pod.yaml b/testdata/valid/pod.yaml
index 3919442..904e9d2 100644
--- a/testdata/valid/pod.yaml
+++ b/testdata/valid/pod.yaml
@@ -1,7 +1,7 @@
 apiVersion:
 kind: Pod
 metadata:
-  name: redis
+  name: ${POD_NAME:redis}
   master: true
 spec:
   containers:
diff --git a/testdata/valid/server.json b/testdata/valid/server.json
index e7edd71..2366a5e 100644
--- a/testdata/valid/server.json
+++ b/testdata/valid/server.json
@@ -1,5 +1,5 @@
 {
-	"host": "0.0.0.0",
+	"host": "${SERVICE_HOST:0.0.0.0}",
 	"logger": {
 		"log_level": "debug"
 	}
diff --git a/testdata/valid/server.test.json b/testdata/valid/server.test.json
new file mode 100644
index 0000000..6fda411
--- /dev/null
+++ b/testdata/valid/server.test.json
@@ -0,0 +1,3 @@
+{
+	"host": "192.168.0.256"
+}
\ No newline at end of file
diff --git a/testdata/valid/server.test.toml b/testdata/valid/server.test.toml
new file mode 100644
index 0000000..1247270
--- /dev/null
+++ b/testdata/valid/server.test.toml
@@ -0,0 +1 @@
+host = "192.168.0.256"
\ No newline at end of file
diff --git a/testdata/valid/server.test.yaml b/testdata/valid/server.test.yaml
new file mode 100644
index 0000000..414070c
--- /dev/null
+++ b/testdata/valid/server.test.yaml
@@ -0,0 +1 @@
+host: "192.168.0.256"
\ No newline at end of file
diff --git a/testdata/valid/server.toml b/testdata/valid/server.toml
index a5ba440..d756bd1 100644
--- a/testdata/valid/server.toml
+++ b/testdata/valid/server.toml
@@ -1,4 +1,4 @@
-host = "0.0.0.0"
+host = "${SERVICE_HOST:0.0.0.0}"
 
 [logger]
 log_level = "debug"
\ No newline at end of file
diff --git a/testdata/valid/server.yaml b/testdata/valid/server.yaml
index c6ddab8..30df7be 100644
--- a/testdata/valid/server.yaml
+++ b/testdata/valid/server.yaml
@@ -1,4 +1,4 @@
-host: "0.0.0.0"
+host: "${SERVICE_HOST:0.0.0.0}"
 
 logger:
   log_level: "debug"
\ No newline at end of file