The psychological sequelae of institutionalized abuse and its long-term consequences has not been systematically documented in existing literature in regarding social support once disclosure has been made. Reporting abuse is crucial, in particular for adult victims of childhood IA within the Catholic Church. Nevertheless, there is ongoing controversy about the benefits of disclosure. Our study examines the interaction of disclosure and subsequent social support in relation to mental health. We look into the times of disclosure, the behaviour during the disclosure to a commission as adults, different level of perceived social support, and the effect on mental health. The data were collected in a sample of financially compensated adult survivors who experienced institutionalized abuse during their childhood, using instruments to measure perceived social support, reaction to disclosure, PTSD, and further symptoms. High levels of perceived social support after early disclosure result in a higher level of mental health and contribute to less emotionally reactive behaviour during disclosure of past institutionalized abuse. Highly perceived levels of social support seem to play a crucial role in mental health, but this inference may be weakened by a possible interference of a lasting competence in looking for social support versus social influences. Future research should thus disentangle perceived social support into the competence of looking for social support versus socially influenced factors to provide more clarity about the positive association of perceived social support and mental health.