Thesis: Ph. D., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages [165]-173).Non-hierarchical, participatory, consensus-based decision making has seen an explosion in popularity in recent years. The traditional techniques of formal consensus, however, are limited to face-to-face meetings, which can limit organizations' capacity due to their time and cost. InterTwinkles is a set of integrated but composable online tools designed to assist small and medium-sized groups in engaging in formal group decision making processes online. In this thesis, I present a thorough investigation of the ethical and practical motivations for consensus decision making, and relate these to concerns of control and autonomy in the design of online systems. I describe the participatory and iterative design process for building an online platform for consensus, with particular attention to the practical constraints of real-world groups with mixed technical aptitude. I present the results of a three month field trial with six cooperative groups in the Boston area, and evaluate the results through the lens of adaptive structuration theory, with particular attention on the fit between the ethical motivations and performance outcomes.by Charles DeTar.Ph. D.