We explored perceived and reported sex (male and female) differences in heterosexual, cisgender undergraduate sexual engagement across 10 common behaviors. Results from 1,007 students suggest that males are perceived to be more sexually engaged than women despite generally no sex differences in reported behavior. Across behaviors, perception versus report comparisons largely demonstrated significant differences. While no sex-related patterns emerged among differences, patterns regarding behavior type did. More standard, objectively defined behaviors (intercourse) demonstrated greater reported engagement than perceived, whereas more promiscuous behaviors (one night stand) demonstrated greater perceived engagement than reported.