In Chapter 1, we introduced you to the history and contemporary development of LGBTQ psychology as a recognised sub-field of psychology. In this chapter, we further equip you to be an LGBTQ psychologist by exploring some of the theoretical and political issues that inform the field. We start by exploring two key debates underpinning much work within LGBTQ psychology: confrontations between essentialist and constructionist theories and between liberal and radical ideologies. Don't panic about our mention of theory, ideology and politics (things that make a lot of psychologists panic!) – these concepts can all be defined simply as an organised collection of ideas, a way of looking at things, a way of explaining things. At the same time, we acknowledge that these debates are rather complex and we encourage you to return to them once you have read some of the topic-based chapters and you have an understanding of the empirical research on which these debates are brought to bear.

In discussing the essentialism versus social constructionism debate we touch on a controversial issue – the aetiology or origins of homosexuality. Our view is that research on the aetiology of homosexuality is deeply problematic, as we explain below.