This Small Business Innovation Research (SBIR) Phase II project investigates end-user programming for ensembles of robots. The project focuses on the development of an accessible end-user programming environment so that middle and high school students can create their own custom ensembles or blocks of robots and observe how the blocks' behavior affect an entire robot. Building powerful and correct intuitions about the behavior of complex systems is important for scientists and engineers, but with today's technologies it is difficult for children to acquire and integrate these ideas into their mindset. Through exploratory play with the proposed robotics construction kit, which embodies a distributed processing scheme for embedded microprocessors, children can build and observe complex systems acting in the real world. Although end-user programming environments exist for software systems, and even for a few robotics toys, no competing approach to end user programming tackles distributed processing for modular robotics. The project aims to build three experimental systems: a text-based environment, a visual programming language, and a 'cellular automata' interface. Testing with local middle school students will determine the benefits and drawbacks of each approach. <br/><br/>The broader/commercial objective of the project is to give children a vehicle to explore how complex global behaviors emerge from local effects. Designing and building complex systems exposes children to a variety of science, technology, engineering and mathematics (STEM) concepts. The programmed kit, without the end-user programming component proposed here, already introduces these important concepts. The addition of an intuitive, low-threshold, high-ceiling approach to reprogramming individual modules will add extensibility to this already powerful model of complexity. A commercial version of kit will be released in three phases: to science centers and children's museums initially, to a core community of technically savvy enthusiasts, and finally to the public through retail channels. Several science centers have expressed serious and persistent interest in acquiring initial versions of the kits and incorporating them into robotics education programs and exhibits. In addition to the project's primary objective, the design and testing of end-user programming for distributed embedded computing can inform other applications of this technology in the rapidly growing area of modular robotics.