This course provides a format for students ready to develop entrepreneurial plans for specific environmental businesses. There are two aspects to any business: knowing the technical subject, and understanding the business environment. It is assumed that students have a background in both aspects, and this course is to enable the students to work in groups to “flesh out” a business. The course has regular meetings, but much of the work—and reporting—is done by the students, with advice and input from the faculty and others at Yale and in the business world. The course (and its prerequisite) may be used in conjunction with competing for the Sabin Prize.