The primary aim of the research was to investigate the sexual health and relationships knowledge of people with learning disabilities (LD). This was to clarify the details of knowledge held, and to identify gaps and misunderstandings, which could be translated into practical implications helping to design better educational and personal support. The project is divided into three studies. Study 1 concentrated on assessment of the sexual health knowledge, experiences and needs of people with LD. Interviews with 27 people with LD were conducted. The data was analysed in two ways: quantitative summaries of answers to the questionnaire measuring sexual health knowledge, and qualitative analysis, which focused on incorrect answers and misunderstandings. Study 2 was an on-line survey for parents of people with LD. Caregivers (n = 83) were asked about their perceptions of the sexual health knowledge of their children. Study 3 was conducted using semi- structured interviews with teachers (n = 15) involved in delivery of sex education to people with LD. The data was analysed using Framework Analysis. The results of my studies show that the knowledge concerning sexual health and relationships of people with LD is highly variable, from very simplistic to full awareness of issues related to sex and relationships. Sexual and relational experiences of people with LD are varied. The sex-related parent-child communication was shown to be related to the perceived sexual health knowledge of children with LD as assessed by parents. Parental neuroticism was associated with the level of perceived knowledge of the children. Teachers and educators who took part in the Study 3 talked about general difficulties when working with people with LD, but also about challenges specific to the subject. They shared their tips, advice and good practice. Based on the results of the studies, many practical recommendations regarding sex education, interviewing people with LD, support for parents and teachers are presented.