WorkingWiki is a software extension for MediaWiki that makes a wiki into a powerful environment for collaborating on publication-quality manuscripts and software projects. The WorkingWiki extension allows you to store "source files" in your wiki and develop, test, run, and publish them easily. Examples include a project of five LaTeX files and six EPS images that compile together into a single PDF file, or an R script that includes two other R source files and produces a CSV data file and several EPS figures. The WorkingWiki extension keeps track of when the source files have changed and when to redo the processing to update the output, and how to display the various file formats involved. The output files and images can be displayed in wiki pages along with the source code, and can be used as inputs to further computations.