Greenfoot is an educational integrated development environment aimed at learning and teaching programming. It is aimed at a target audience of students from about 14 years old upwards, and is also suitable for college- and university-level education. Greenfoot combines graphical, interactive output with programming in Java, a standard, text-based object-oriented programming language. This article first describes Greenfoot and then goes on to discuss design goals and motivations, strengths and weaknesses of the system, and its relation to two environments with similar goals, Scratch and Alice. (Contains 9 figures and 3 footnotes.)