Introduction There is a dearth of research to guide acute adolescent mental health inpatient care. Self-determination Theory provides evidence that meeting needs for relatedness, autonomy and competence is likely to increase wellbeing and intrinsic motivation. These needs may be able to be met in the inpatient environment. Method This qualitative study aimed to explore young peoples experience of acute mental health inpatient care with particular attention to meeting of these three needs. Fifteen young people were interviewed. The importance of relatedness with staff, other young people and families was identified. Results Relatedness with staff and peers were valued parts of admission. Some young people describe enhanced relatedness with family. They described loss of autonomy as a negative experience but appreciated opportunities to be involved in choices around their care and having more freedom. Coming into hospital was associated with loss of competence but they described building competence during the admission. Engaging in activities was experienced positively and appeared to enhance meeting of all three needs. Meeting of the three needs was associated with an experience of increased safety. Conclusions Engaging young people in activities with a focus on relatedness, autonomy and competence may have specific therapeutic potential. Autonomy, experience of competence and connection with staff may enhance safety more effectively than physical containment. Peer contact may have untapped therapeutic value we understand little of. This study supports the value of Self-determination Theory as a guide day to day inpatient care to meet the needs of adolescents for relatedness, autonomy and competence.