Composing music for ensembles of computer-based instruments, such as laptop orchestra or mobile phone orchestra, is a multi-faceted and challenging endeavor whose parameters and criteria for success are ill-defined. In the design community, tasks with these qualities are known as wicked problems. This paper frames composing for computer-based ensemble as a design task, shows how Buchanan’s four domains of design are present in the task, and discusses its wicked properties. The themes of visibility, risk, and embodiment, as formulated by Klemmer, are shown to be implicitly present in this design task. Composers are encouraged to address them explicitly and to take advantage of the practices of prototyping and iteration.