Donor sperm treatment has been controversial as it represents a fundamental shift away from traditional family building. The treatment, nowadays in the Netherlands an option for heterosexual couples, lesbian couples and single women, involves wide-ranging and long-lasting psychosocial implications for families and donors involved in donor conception. This thesis aims to explore the formal and informal support needs of intended parents, parents and donor-conceived offspring. It also aims to explore the relationship between any unmet support needs and mental health of these families. We found that psychosocial counselling is valued by intended parents and parents but that it is not available for all of them – and when offered – not always in line with their support needs. Unmet support needs are negatively related to mental health of (intended) parents and the mental health of donor-conceived offspring. Social support in terms of support from friends, family and peers is valued at the time men and women opt for donor sperm treatment and after their children have been born. By donor-conceived offspring themselves, the need for support in accessing trustworthy information about donors, and for counselling to be available to those who need it is also acknowledged. Providing opportunities for all parties involved in donor sperm treatment to have access to psychosocial counselling is critical to ensure safe practice of donor sperm treatment. As the bigger picture also includes sperm donors, we recommend to gain knowledge about their support needs and the psychosocial impact of gamete donation on donors and their families.