This SAGE Research Methods Dataset example provides an introduction to the concepts behind Age Period Cohort (APC) analysis and some basic methods for carrying it out using longitudinal data. In this example, we use the case of attitudes towards the lifestyles of gay and lesbian citizens and how these have changed in the UK between 2002 and 2014. We show some basic ways to analyse these changes that can help us understand the kinds of dynamic social processes at work and point out the limitations of these methods, using data from the European Social Survey (ESS). The dataset file is accompanied by a Teaching Guide, a Student Guide, and a How-to Guide for Stata