The chapter presents the science approach to HCI research, including an illustration from the literature. The latter presents the case for developing new forms of psychology deep theory, based on generic systems of interactors. The chapter then presents the specific science framework for HCI research comprising science as discipline, general problem, particular scope, research, knowledge and practices. The specific science framework is followed by the science design research exemplar, as the science design cycle, the applied design research cycle and the science design research cycle. The lower-level science framework comprises the science application, the science interactive system, and the science interactive system performance. Both the exemplar and the lower-level framework are applied to the same illustration of the science approach, taken from the literature, which presents the case for developing new forms of psychology deep theory, based on generic systems of interactors.