We study the molecular mechanisms that underlie cell polarity using a combination of high-throughput protein interaction mapping approaches and in vivo studies using the model organism C. elegans. Cell polarity is critical to animal development and tissue functioning, and defects in polarity are an important factor in the development of cancer and other diseases. Polarization of cells and tissues requires assembly of a variety of protein complexes that include scaffolding proteins with multiple protein binding domains. Identifying which proteins interact and how they interact is therefore an excellent starting point to improve our understanding of polarity establishment.