In a wide variety of settings, organizations generate a number of possible solutions to a problem—ideas—and then select a few for further development. We examine the effectiveness of two group structures for such tasks—the team structure, in which the group works together in time and space, and the hybrid structure, in which individuals first work independently and then work together. We define the performance of a group as the quality of the best ideas identified. Prior research has defined performance as the average quality of ideas or the number of ideas generated, ignoring what most organizations seek, a few great ideas. We build a theory that relates organizational phenomena to four different variables that govern the quality of the best ideas identified: (1) the average quality of ideas generated, (2) the number of ideas generated, (3) the variance in the quality of ideas generated, and (4) the ability of the group to discern the quality of the ideas. We test this theory with an experiment. We find that groups organized in the hybrid structure are able to generate more ideas, to generate better ideas, and to better discern the quality of the ideas they generate. Moreover, we find that the frequently recommended brainstorming technique of building on others' ideas is counterproductive; teams exhibiting such buildup neither create more ideas, nor are the ideas that build on previous ideas better.