The participation of young women sex workers in Human Immunodeficiency Virus (HIV) policies and programmes is necessary for addressing HIV among this most-at-risk population. The Thai government has recently made a commitment to increase sex workers’ participation levels in HIV interventions; this study sets out to explore this issue. Young women constitute a very high proportion of sex workers in Thailand and experience greater vulnerability than older sex workers; it is therefore of great importance that they play a key role in participation. This study asked: To what extent do young women sex workers in Bangkok, Thailand participate in HIV policies and programmes? Five young women sex workers from Bangkok were interviewed regarding their views and experiences of participation in HIV policies and programmes. Staff from a Civil Society Organisation (CSO), working with young women sex workers took part in a small focus group discussion to gain their insights on this issue. The findings identified a number of challenges and barriers to participation, with few examples of meaningful participation. The challenges and barriers to participation in HIV policies and programmes in Thailand were related to; fear and trust of the authorities; stigma; the illegal nature of sex work and other aspects of the sex industry; low educational levels and the subordinate position of young women in Thai society. Some examples of sex worker participation today appear to follow the peer education model. These were however found to be under-resourced, lacked organisation and were not based on an empowerment model of participation. Participation by young women sex workers at the CSO level included some input into the national prevention strategy, but was found to be largely tokenistic. This study displays the alarming situation currently faced in regards to young sex worker participation in HIV policies and programmes. It is however encouraging to note that young women sex workers who participated in the research demonstrated a desire for greater involvement in HIV policies and programmes in a meaningful way. Greater participation may aid in identifying innovative approaches for improving sex worker-targeted HIV policies and programmes, even within this resource constrained environment. It is crucial that sex worker collectives play a leading role in supporting and advocating for young sex worker participation. Also of great importance is the role of powerful actors such as donors, the Thai government and non-government organisations in supporting the efforts of sex worker collectives.