Abstract Background: Sexual Health and Relationship Education ( provides individuals with the knowledge and skills set which helps them to manage risky behaviours and make informed decisions and to protect themselves against STIs, risky behaviour, and unintended pregnancy. Such education is minimally provided in Iranian schools and universities; and previous research has indicated a demand and the need for SHRE among young people across the social spectrum (Chapter 1). Aim: The overall aims of this project were to ( conduct a needs assessment of the SHRE and sexual health service needs of young adults living in Tehran, ( investigate how such provision could be improved or augmented, taking the account of the views of health professionals and policymakers, and ( design a tailor-made SHRE programme for the future development of improved provision to be delivered in Tehran. Methods: This PhD project explored Iranian young adults’ sexual health education, training, and service needs and ways to improve or augment the existing provision (Chapter 3). This was followed by an investigation of Iranian healthcare professionals’ assessments of, and recommendations for, sexual health education and service provision for young people in Tehran (Chapter 4). Both of these studies employed detailed thematic analyses of interview transcripts. Finally, a tailor-made programme outline for an improved SHRE provision for young adults in Tehran was developed based on the findings of the first two studies, recommendations made in international guidance on the optimal content of SHRE programmes, and further stakeholder consultations using a public involvement methodology (Chapter 5). Results: Young adults in Tehran expressed their need and demand for enhanced sexual health education and healthcare. They highlighted existing barriers such as almost non-existent official education and the lack of reliable resources, taboo and cultural barriers, and lack of trust and confidentiality when seeking sexual health information, advice, and healthcare. This has resulted in ambiguities and misconceptions, including those regarding the cause and transmission of STIs and the correct use of contraception methods. They unanimously expressed their dissatisfaction with available sexual health education and provided recommendations for an improved provision, including holding mixed-gender extracurricular workshops with a comprehensive approach to sexual health and relationship education (Chapter 3). Validating young adults’ views, healthcare professionals emphasised the need for improved SHRE and service provision for young adults. They also confirmed the barriers highlighted by young Tehranians and collectively supported the augmentation of educational provision and healthcare services and provided recommendations on how this could be achieved (Chapter 4). A bespoke SHRE programme was then developed based on the aforementioned needs assessments, in addition to comments from the programme’s stakeholders and best practice guidelines published by six national and international organisations. The programme provides content and delivery recommendations, along with objectives and deliverables for each content category. The final programme outline is intended as a blueprint for improved SHRE provision in Tehran, and potentially Iran (Chapter 5). Conclusion: This PhD project has generated two novel in-depth needs assessments complemented by a theory- and evidence-informed, tailor-made SHRE programme outline which has the potential to augment the currently minimal SHRE provision in Tehran. This enhanced programme will have the capacity to provide young adults with reliable and non-judgmental sexual health and relationship knowledge and skills, which can result in improved sexual health and confidence in managing healthy relationships. Overall, this research demonstrates the unmet needs and desires of Tehranian young adults and healthcare professionals concerning sexual health and relationship education. It provides several recommendations for the future development and implementation of SHRE programmes in Tehran.