A psychoeducation program that was originally developed by the Dutch Association for Autism was adjusted for older adults to enhance its feasibility and efficacy in later life. In this study, we explored the effects of this adapted psychoeducation program for older autistic adults in a pre-test -- post-test 6-month follow-up design. A total of 61 patients (55-78 years) and 44 proxies (a person close to them) participated in the study; attrition rate was high for the follow-up assessment. As hypothesized, an increase in knowledge and acceptance of the diagnosis was observed, with a strong and positive correlation between patients and proxies for knowledge. Furthermore, ambiguous results were observed on coping with the diagnosis and no positive effects on psychological distress were found. The feedback of participants and proxies about the psychoeducation program was largely positive. Future research with larger group samples and larger time scales is necessary to gain more insight into the effectiveness of the psychoeducation program. It seems worthwhile to further adjust the program to the needs and requirements of older adults, and to help older autistic adults to construct a new narrative of themselves, and the life they have lived, in the light of the recent autism diagnosis.