As firms engage in an increasing number of alliances, they face the challenge of managing such an alliance portfolio. Although existing studies on alliance portfolio management (APM) mainly focus on (i) alliance experience and (ii) APM best practices, they remain silent on how firms structurally design their APM system. On the basis of the survey data of 103 companies that engaged in technology alliances between 2006 and 2008, we identify four first-order (APM formalization, APM hierarchy, APM specialization, and APM participation) and two second-order (mechanistic APM and organic APM) dimensions that explain how firms design the management of their technology alliance portfolios. In addition, we find that adopting an organic approach toward designing APM significantly increases alliance portfolio performance, suggesting that particular APM designs might contribute to building alliance management capabilities. Copyright © 2013 John Wiley & Sons, Ltd.