Inadvertent plagiarism, or cryptomnesia, occurs when an individual claims another's idea as his or her own with no recollection of having been exposed to the idea before. Although some variation exists in the explanations of this occurrence, the source monitoring framework has emerged as the most plausible account. The purpose of this paper is to review the core body of research that has been conducted on cryptomnesia over the past two decades, with particular focus on the factors that affect the propensity of this phenomenon and how these influences inform a theoretical explanation of cryptomnesia. This paper also includes some suggestions for how future research might continue to explore the phenomenon of inadvertent plagiarism.