diff --git a/Project.toml b/Project.toml
index d3b9a52..42296bc 100644
--- a/Project.toml
+++ b/Project.toml
@@ -3,5 +3,12 @@ uuid = "13e0c4e3-fd7a-51bf-9e22-ec7679f18909"
 authors = ["Daniel Matz <daniel.a.matz@nasa.gov>"]
 version = "0.2.0"
 
+[weakdeps]
+Unitful = "1986cc42-f94f-5a68-af5c-568840ba703d"
+
+[extensions]
+UnitfulExt = ["Unitful"]
+
 [compat]
+Unitful = "1"
 julia = "1"
diff --git a/ext/UnitfulExt.jl b/ext/UnitfulExt.jl
new file mode 100644
index 0000000..158b6ca
--- /dev/null
+++ b/ext/UnitfulExt.jl
@@ -0,0 +1,34 @@
+module UnitfulExt
+
+using COESA
+import COESA:
+    atmosphere,
+    altitude,
+    mean_molecular_weight,
+    temperature,
+    pressure,
+    density,
+    speed_of_sound,
+    dynamic_viscosity
+
+using Unitful
+
+struct UnitfulState
+    state::COESA.State
+end
+
+altitude(s::UnitfulState) = altitude(s.state) * u"m"
+mean_molecular_weight(s::UnitfulState) = mean_molecular_weight(s.state) * u"kg/kmol"
+temperature(s::UnitfulState) = temperature(s.state) * u"K"
+pressure(s::UnitfulState) = pressure(s.state) * u"Pa"
+density(s::UnitfulState) = density(s.state) * u"kg/m^3"
+speed_of_sound(s::UnitfulState) = speed_of_sound(s.state) * u"m/s"
+dynamic_viscosity(s::UnitfulState) = dynamic_viscosity(s.state) * u"N*s/m^2"
+
+function atmosphere(Z::Quantity)
+    Z′ = ustrip(u"m", Z)
+    state = atmosphere(Z′)
+    UnitfulState(state)
+end
+
+end
diff --git a/test/Project.toml b/test/Project.toml
index 737dfda..1368296 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -2,3 +2,4 @@
 Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
 JET = "c3a54625-cd67-489e-a8e7-0a5a0ff4e31b"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+Unitful = "1986cc42-f94f-5a68-af5c-568840ba703d"
diff --git a/test/runtests.jl b/test/runtests.jl
index 67b8c62..657cb46 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -2,6 +2,9 @@ using COESA
 using Test
 using Aqua
 using JET
+using Unitful
+
+quantity_type(T, units) = Quantity{T, dimension(units), typeof(units)}
 
 M0 = COESA.M0
 
@@ -239,6 +242,17 @@ M0 = COESA.M0
         @test_throws ErrorException dynamic_viscosity(atmos)
     end
 
+    @testset "Unitful Extension" begin
+        atmos = atmosphere(0u"m")
+        @test altitude(atmos) == 0u"m"
+        @test round(quantity_type(Float64, u"kg/kmol"), mean_molecular_weight(atmos), sigdigits = 5) == 28.964u"kg/kmol"
+        @test round(quantity_type(Float64, u"K"), temperature(atmos), sigdigits = 6) == 288.150u"K"
+        @test round(quantity_type(Float64, u"Pa"), pressure(atmos), sigdigits = 6) == 101325u"Pa"
+        @test round(quantity_type(Float64, u"kg/m^3"), density(atmos), sigdigits = 5) == 1.2250u"kg/m^3"
+        @test round(quantity_type(Float64, u"m/s"), speed_of_sound(atmos), sigdigits = 5) == 340.29u"m/s"
+        @test round(quantity_type(Float64, u"N*s/m^2"), dynamic_viscosity(atmos), sigdigits = 5) == 1.7894e-5u"N*s/m^2"
+    end
+
     @testset "Code Quality" begin
         @testset "Aqua" begin
             Aqua.test_all(COESA, project_extras = false)