With the introduction of generative and parametric systems for architectural design, the amount of iterations an architect can produce has become limitless. However, as architects continue to negotiate complex design problems requiring iterations, variations, and alternatives, it becomes necessary to simultaneously formulate systems for evaluation and validation. Genetic algorithms and evolutionary systems provide a framework by which optimal solutions can be searched for within an infinite generative field of variation. Using these tools, the parametric system becomes the genome, the field of alternatives becomes the population, and the architect’s design goal becomes the fitness criteria. This class will introduce students to the world of evolutionary systems with the aim of promoting a process for interrogating design alternatives as well as the systems used to generate them. The class will focus on the use of the Grasshopper algorithm editor for Rhino with specific attention to the evolutionary solver: Galapagos. Students will be challenged to construct parametric design systems and use the Galapagos solver to find optimal results based on the user-defined design criteria.