We study how the nervous system controls behavior by analyzing the simple neural networks that control spatial orientation and decision making in the nematode worm Caenorhabditis elegans. C. elegans has a small nervous system (302 neurons), whose neurons and connectivity pattern have been exhaustively characterized. Together with an entirely sequenced genome and high accessibility to genetic analysis, this organism provides a unique opportunity to study the neural, molecular, and genetic basis of intelligent behavior. Our research integrates a wide range of approaches, including quantitative analysis of behavior, neuronal ablation, computer modeling, electrophysiology, calcium imaging, optogenetics, and microfluidics.