Collaboration provides learners with opportunities to develop an understanding beyond what they could achieve alone. To this end, learners need to build on each other's knowledge to draw new conclusions. This requires successful retrieval, inferencing, and mutual referencing during collaboration. Although individual preparation is considered as effective means to foster these processes it has not been systematically investigated whether, why, and under what conditions it does so. We revisit research on collaborative learning, collaborative memory, and group brainstorming to develop hypotheses about the cognitive advantages and disadvantages of individual preparation for collaboration and how these might be influenced by the design of the individual preparation phase. Subsequently, we test these hypotheses by systematically reviewing experimental studies. Results indicate that (a) individual preparation affects retrieval, inferencing, and referencing differently, and (b) generative preparation tasks and supporting learners' cognitive group awareness can enhance the advantages and mitigate the disadvantages of individual preparation for collaboration.