Stomata are small adjustable pores on the surface (epidermis) of land plants that act as a main conduit for gas exchange. They not only play an essential role in photosynthesis of green plants but also exert an important influence on the global carbon and water cycle. There are great differences between monocots and dicots in distribution and morphological structure of the stomata, affecting the species-specific regulation of stomatal development. In this review, we summarize the molecular regulation networks associated with stomatal precursor cell fate determination and the epigenetic mechanisms on regulation of polar cell division. We also outline the stomatal development processes mediated by crosstalk between exogenous and intrinsic signals, and propose a model of multilevel regulation of stomatal development.