Unsafe sex can lead to unwanted pregnancies and sexually transmitted infections. Traditionally, safer sex interventions have promoted condom use in ‘high risk’ populations. This approach ignores the wider complexities of condom use, particularly the fact that safer sex requires a process of five condom-related behaviours; accessing, carrying, negotiating, using and disposing. Furthermore, safer sex is relevant to all individuals across the lifespan. Thus omitting ‘low risk’ populations from interventions may be contributing to the continual rise in STIs in the UK. Theory can be useful as a framework for exploring behaviour and developing interventions. This book therefore, provides a new approach to exploring condom-related behaviours and delivering an intervention in a broad population. It will be useful to students wishing to understand how theory can be used to explore a real-world problem, and also useful for health care professionals with an interest in intervention development. Data presented in this book illustrates the stages of intervention development.