In this commentary, the authors discuss the implications of A. S. Green, E. Rafaeli, N. Bolger, P. E. Shrout, and H. T. Reis's (2006) diary studies with respect to memory. Researchers must take 2 issues into account when determining whether paper-and-pencil or handheld electronic diaries gather more trustworthy data. The first issue is a matter of prospective memory, and the second is a matter of reconstructive memory. The authors review the research on these issues and conclude that regardless of the type of diary researchers use, several factors can conspire to produce prompt--but inaccurate--data.