I will introduce a new, simple model that self-consistently connects the growth of galaxies to the formation history of their host dark matter halos. Using just two simple, phenomenologically motivated equations that depend only on dark matter halo properties, our "formation history" model is capable of reproducing the observed z=0 red and blue stellar mass functions. By adding redshift as a second input variable to the model I will further show that an improved reproduction of the stellar mass function out to z=3 can be achieved. Finally, I will discuss the general utility of this new model for exploring a broad range of topics associated with galaxy formation and evolution, and for creating mock galaxy samples which have a number of advantages over those generated by other techniques.