How many different types of cells are there in an animal? For the C. elegans nematode, the answer is known, because the entire cell lineage has been defined. However, the extent to which each of the cells in the worm has a distinct gene expression profile is not known. In collaboration with the labs of Bob Waterston and Jay Shendure, we recently reported the gene expression profile for every cell in the worm at the L2 larva stage. Our study constitutes our first step on the path to building a complete atlas of RNA expression for the worm. You can dive into our data and build on or modify our analysis code, both of which are freely available. As we profile the other stages of the worm’s development, we will deposit our data and analysis on the web. We invite others to help us analyze this data to map the molecular profiles onto the worm’s cellular lineage.