This course illustrates how social factors influence even the very personal realms of sex and love, and how these topics can be studied scientifically. Focusing on modern societies, topics include dating and romantic relationships; relational and casual sex; contraception and unintended pregnancy; heterosexual, gay, lesbian, and bisexual sexualities; cultural attitudes toward sexuality; changing meanings of marriage. The aim of the course is to expose students to sociological research on sexuality and love. Students often like taking courses on this topic because they are personally interested in the topic. I am happy to have such students, but I explain at the outset that the fact that we are studying a “fun” topic does not mean that this is not a rigorous course. As with other courses, the focus should be dual: that they are exposed to the substance of research on the topic, and that they learn about the way social scientists do research and draw conclusions from data analysis.