diff --git a/src/core/defcomp.jl b/src/core/defcomp.jl
index 2b8da496d..1f8e387e9 100644
--- a/src/core/defcomp.jl
+++ b/src/core/defcomp.jl
@@ -25,7 +25,8 @@ function _generate_run_func(comp_name, module_name, args, body)
         global function $(func_name)($(p), #::Mimi.ComponentInstanceParameters,
                                      $(v), #::Mimi.ComponentInstanceVariables
                                      $(d), #::NamedTuple
-                                     $(t)) #::T <: Mimi.AbstractTimestep
+                                     $(t); #::T <: Mimi.AbstractTimestep
+                                     get_dim_keys::Function) #::Function
             $(body...)
             return nothing
         end
diff --git a/src/core/instances.jl b/src/core/instances.jl
index 4ba0cad1a..13e1fd578 100644
--- a/src/core/instances.jl
+++ b/src/core/instances.jl
@@ -312,18 +312,18 @@ function get_shifted_ts(ci, ts::VariableTimestep{TIMES}) where {TIMES}
     end
 end
 
-function run_timestep(ci::AbstractComponentInstance, clock::Clock, dims::NamedTuple)
+function run_timestep(ci::AbstractComponentInstance, clock::Clock, dims::NamedTuple, get_dim_keys::Function)
     if ci.run_timestep !== nothing && _runnable(ci, clock)
-        ci.run_timestep(parameters(ci), variables(ci), dims, get_shifted_ts(ci, clock.ts))
+        ci.run_timestep(parameters(ci), variables(ci), dims, get_shifted_ts(ci, clock.ts); get_dim_keys=get_dim_keys)
     end
 
     return nothing
 end
 
-function run_timestep(cci::AbstractCompositeComponentInstance, clock::Clock, dims::NamedTuple)
+function run_timestep(cci::AbstractCompositeComponentInstance, clock::Clock, dims::NamedTuple, get_dim_keys::Function)
     if _runnable(cci, clock)
         for ci in components(cci)
-            run_timestep(ci, clock, dims)
+            run_timestep(ci, clock, dims, get_dim_keys)
         end
     end
     return nothing
@@ -359,11 +359,19 @@ function Base.run(mi::ModelInstance, ntimesteps::Int=typemax(Int),
     # into timestep arrays.
     dim_val_named_tuple = NamedTuple(name => (name == :time ? timesteps(clock) : collect(values(dim))) for (name, dim) in dim_dict(mi.md))
     
+    # Define dim_keys, a function that allows the component to return the keys
+    # of a given dimension. This is passed through and serves as a keyword argument
+    # to the run_timestep function of each component so they may access the dimension
+    # key information.
+    function get_dim_keys(dim_name::Symbol)
+        return dim_keys(mi, dim_name)
+    end
+
     # recursively initializes all components
     init(mi, dim_val_named_tuple)
 
     while ! finished(clock)
-        run_timestep(mi, clock, dim_val_named_tuple)
+        run_timestep(mi, clock, dim_val_named_tuple, get_dim_keys)
         advance(clock)
     end
 
diff --git a/test/test_components.jl b/test/test_components.jl
index e5aba0d22..2b7da2c6f 100644
--- a/test/test_components.jl
+++ b/test/test_components.jl
@@ -160,4 +160,35 @@
     ci = compinstance(m, :C) # Get the component instance
     @test ci.first == 2010      # The component instance's first and last values are the same as the comp def
     @test ci.last == 2090
+
+    # 3. Test using the dim_keys function in run_timestep
+    my_model = Model()
+    set_dimension!(my_model, :time, 2000:2010) # Set the time dimension
+    set_dimension!(my_model, :region, [:A, :B, :C]) # Set the region dimension
+
+    @defcomp testcomp5 begin
+
+        var1 = Variable(index=[time])
+        par1 = Parameter(index=[time])
+
+        var2 = Variable{Int}(index=[region]) # hold region idxs 1:n
+        var3 = Variable{Symbol}(index=[region]) # hold region keys
+
+        function run_timestep(p, v, d, t)
+            v.var1[t] = p.par1[t]
+            for region in d.region
+                v.var2[region] = region
+                v.var3[region] = get_dim_keys(:region)[region]
+            end
+        end
+    end
+
+    add_comp!(my_model, testcomp5)
+    update_param!(my_model, :testcomp5, :par1, collect(1:11))
+
+    run(my_model)
+
+    @test my_model[:testcomp5, :var2] == [1,2,3]
+    @test my_model[:testcomp5, :var3] == [:A, :B, :C]
+
 end