Humans tend to automatically imitate others. This tendency is generally explained by a common representation of observed and executed actions. However, people do not imitate each and any behavior they observe. Instead, they have different possibilities in terms of when, what, and whom they imitate. Here, we review the literature on the various factors that modulate imitative behavior to get an overview of these possibilities. While the reviewed literature supports the idea of possibilities in terms of how people imitate, this overview also emphasizes that the evidence for most factors has been rather mixed or preliminary. This calls for more replication studies, both conceptual and direct, before firm conclusions can be made for each modulating factor.