Embryonic development begins with the fertilization of an oocyte by a sperm. The ensuing developmental events, including pronuclear fusion and cell division, are conducted by maternally and paternally provided gene products. Even after zygotic gene expression has initiated, perduring maternal factors continue to function in developmental programs for cell fate specification and morphogenesis. The vertebrate zebrafish Danio rerio has emerged as a valuable model for the identification of these maternal and paternal factors. In this review, we will describe recent efforts to identify these genetic players and discuss our current understanding of their function in early developmental events.