This clinic will offer you an introduction to developing food web models using Ecopath with Ecosim software. Ecopath with Ecosim (EwE) is an ecological modeling software suite for personal computers that has been built and extended on for over thirty-five years. EwE is the first ecosystem level simulation model to be widely and freely accessible. EwE is the most applied tool for modeling marine and aquatic ecosystems globally, with over 400 models published to date, making EwE an important modeling approach to explore ecosystem related questions in marine science. In addition, Ecopath software was recognized as one of NOAA’s top ten scientific breakthroughs in the last 200 years. In this clinic, we will start with a brief introduction, then download the freeware and start setting up some simple models which we will use in example exercises. Note: the software works in a Windows environment; Mac computers can be used if they are set up with Parallels Desktop or a similar application to run programs in a Windows environment on a Mac.