Organizations use innovation contests to enable crowdsourcing for open innovation. While the crowd is able to generate large amounts of ideas in such contests, the challenge shifts to subsequent idea selection. This study systematically reviews the selection mechanisms that the literature has so far discussed for this purpose. Findings are structured using an analytical framework along selection process phases of preprocessing, shortlisting, selecting finalists as well as according to whether the crowd, small teams, automated or hybrid combinations of agents perform the selection. An agenda for further research is proposed based on these findings, emphasizing the need for research on selection mechanisms to process crowdsourced ideas.