In this paper, we examine digital creativity as a collective activity performed through socio-technological networks of agency. We introduce metacreation—the automation of creative tasks with machines—as a domain that is usefully examined from a 3rd wave HCI approach. We discuss four general human-computer interaction activities that commonly appear in metacreation: (1) metagenerating form; (2) searching/finding; (3) helping machines learn; and (4) evaluation/iteration. These are not necessarily specific to metacreation, but nevertheless point to particular design considerations in a metacreative context. Four creative interaction design themes are considered in their relation to metacreation: direct manipulation and real-time control; supporting playful interaction and divergent goals; the programmatic design of behaviours, and; managing distributed creativity. We then identify three paradigms of interaction design for metacreation: operation-based interaction, involving the direct manipulation of generative algorithms; request-based interaction, involving the submission of requests to a system that returns results; and ambient interaction, that involves the operation of autonomous metacreative processes in the background. Our discussion of these suggests possible trends for design: an increasingly complex and modular future for networked human-machine digital creativity; an increasing role for request-based metacreative systems where users specify, rather than construct, outcomes; the increasing role of metacreation in "prosumer" content creation; and, consequently, the reduction of labour involved in creating media. The chapter makes clear, we hope, that metacreative practices present unique challenges and opportunities for interaction design.