This article describes and explains a sustainability law practicum class that is now taught in only two law schools, but which has considerable teaching and practical value. It also explains how this class is consistent with, and furthers, the growing demand for experiential, skills-based legal education employing formative assessment. The class uses a realworld setting to provide students with skills they will need to help clients meet their sustainability goals. These skills include application of the principles of sustainable development in specific contexts; researching local government law; legislative/ordinance drafting; giving short presentations; and client counseling. These skills are developed in the course through a semester-long project involving drafting sustainability-related ordinances (e.g., green roofs, composting) for an actual municipality or municipal government trade association.