Though many neuronal cell fate decisions result in reproducible outcomes, stochastic choices often lead to spatial randomization of cell subtypes. This is often the case in sensory systems where expression of a specific sensory receptor gene is selected randomly from a set of possible outcomes. Here, we describe recent findings elucidating the mechanisms controlling color photoreceptor subtypes in flies and olfactory receptor subtypes in worms and mice. Although well-known biological concepts such as lateral signaling and promoter selection play roles in these cases, fundamental questions concerning these choice mechanisms remain.