Pattern-forming systems provide essential spatial cues to guide the complex three dimensional puzzle that is organismal development. Work over the past decades has identified most of the key molecules involved, yet we are only beginning to understand how the collective activities of these molecules give rise to patterns at the cell and tissue scale. What are the properties of these networks that permit pattern formation? How are pattern boundaries established? What sets the scale of a pattern and how do pattern-forming networks adapt to the changes in the size and shape of cells and tissues that are inherent to the development process? My group applies a multidisciplinary approach to uncover these and other fundamental design principles of pattern-forming systems in the context of the early C. elegans embryo. We currently focus on the PAR cell polarity network, the core function of which is to induce asymmetric localization of molecular determinants within the cell along a specified axis. We are developing tools to measure and manipulate protein dynamics and interactions in live embryos and then using this information to design and test mathematical models for how PAR proteins generate patterns within the cell.