Ideologies provide a set of norms and values that guide our attitudes and behavior in times of uncertainty. Given the private nature of sex, we may be particularly reliant on our pre-existing ideas about the world to guide our actions in the bedroom. Previous research on the influence of social values on sexual behavior has typically focused on group-level processes, for example, research on the cultural suppression of female sexuality (Baumeister & Twenge, 2002). Scholars in the social sciences have discussed the ways in which we internalize social norms and values, and how these might influence our experience of sex, for example through sexual scripts (Gagnon & Simon, 1973). There is, however, limited empirical work testing the association between worldviews, or ideologies, and sexual behavior at the individual level. The aim of the present thesis I feel like the Peter Pan of PhDs, refusing to grow up from my academic childhood, clutching tight to Neverland with my puny fists (that are now quite strong from typing). I have spent the last four years with two of my favourite people, so writing these acknowledgements is hard because it means loosening my firm grasp on them. Matthew Hornseyyou have been the perfect mentor. When I first heard you speak as an undergraduate, I felt a surge of energy. I wanted to tell everybody about the reciprocity principle, but it was like repeating comedy, it just wasn't the same when I said it. Lucky for me, I got to soak up your unrivalled story-telling, wisdom, and wildly fun sense of humour first hand for the past four years. I sometimes worry that my guffaws from your office scare the birds. Thank you for making my PhD a pleasure, Matthew. But know that you've made it devastatingly hard to leave. Fiona Barlowto borrow your words, you might be the love of my life, and I know I'm not yours, but that's ok. Together, we have tackled questions like who's a stud and who's a slut? What makes a woman orgasm? And do sexist men fart in bed? You are always ten steps ahead, Fi, and I suspect, always have been. Your understanding of the world is so sophisticated that you could easily be bored and dismissive of those around you, but you are one of the most inclusive people I know. I sometimes wonder whether you are super-humanare you a wizard, Barlow? While the biggest chunk of the gratitude pie must go to Matthew and Fiona, so many people in my life deserve their own sizeable chunks. Thanks go to my dear friends from the early days