Background: Sexuality is learned through sexual socialisation that women with intellectual disabilities (IDs) understand and express. Rules of sexual engagement for these women can include barriers for their socialisation, intimate partner selection, and sexual expression. These rules can become more limiting when coupled with rules of femininity that encourage sexual restraint for women. Methods: This ethnography explored how women with IDs perceived their sexuality and how sexuality functioned in their lives. Sources of data included 48 multiple and in-depth interviews and observations with 14 women. This article specifically describes how the women constructed "sex" and how they described experiencing sex as two of their multiple expressions of sexuality in this study. Results: Most of the women had very limited and exclusively heterosexual sexual experiences, and the majority of women reported practicing abstinence. Criteria they identified for sex included having protected sex, marital and monogamous sex for the purpose of procreation or parenting, and having feelings for a sexual partner. Most held negative perceptions of sex they attributed to fear of the first act, fear of experiencing negative consequences, physiological concerns about the act, and perceived or actual lack of pleasure. Conclusions: Although the women displayed some sense of self-determinism in their sexual behaviour, negative perceptions of sex resulted in self-imposed abstinence predicated by fear of intercourse, intimacy, or outcome. Central to their sexuality education then is increasing self-efficacy perceptions and performance of safer sex practices to prevent negative sexual consequence. Sexuality education from a positive perspective that enhances their sexual self-determinism and encourages sexual health is recommended.