Research into definitions of "having sex" has tended to employ a dichotomous response design (following Sanders & Reinisch, 1999). However, conceptions of sexual activity may be far less clear-cut (c.f. Faulkner, 2003 ; Peterson & Muehlenhard, 2007). More refinement is also needed regarding the impact of sexual orientation on the construction of what counts as sex. This research employed a continuous response design, asking 124 emerging adults (40 male heterosexuals, 42 female heterosexuals, & 42 lesbians) to judge 13 sexual acts using a graded, six-point scale. Overall, there was substantial agreement that intercourse (vaginal and anal) was "definitely," and kissing "definitely not," sex. However, across the various acts, participants also consistently made use of options between these extremes, such that a clear hierarchy of sexual behaviors emerged. The lesbian group considered a range of forms of genital stimulation to be significantly more constitutive of sex than either heterosexual group, while judgments by male and female heterosexuals did not significantly differ for any listed act. The implications of graded definitions of sex, a hierarchy of sexual behaviors, and the role of sexual behaviors in hetero- and homosexual identity management are explored.