Methods and apparatus, including computer program apparatus, implementing techniques for designing sets of combinatorial experiments. A set of experimental parameters, sampling patterns, and constraints defines a set of experiments that is limited to a volume of a hyperspace defined by the set of experimental parameters. Parameters can be grouped by type such that grouped parameters are constrained to perform a common role in the set of experiments. The practicability of the experiment design can be estimated based on the number of experiments in the set of experiments. The experiment design can be used to prepare one or more combinatorial libraries.