The ability to generate genetic variants has greatly aided the study of biochemical and developmental pathways. Given the success of this approach it is not surprising that genetics is being used to address a wide range of neurobiological questions including the generation of behaviour. My laboratory uses the larval visual system of the fruit fly Drosophila melanogaster as a model system to investigate the mechanisms underlying the development and function of the nervous system. To that end, mutations or molecular tools are used to impair specific cell types and/or cellular interactions. Mutations found to disrupt the development of the larval visual system or the larval response to light can be used to identify molecules involved in these processes. Thus, my research program can be divided in two parts namely the genetic analysis of the larval response to light and the molecular genetic analysis of genes required for the development of the larval visual system. To address these questions a variety of techniques are used such as mutant analysis, molecular and cell biology.