In disability research, there is an increased focus on the well-being of families with a child with a disability, also known as family quality of life (FQOL). However, the well-being of families with a child with profound intellectual and multiple disabilities (PIMD) has not yet been explored, even though their well-being may be affected by the pervasive support needs they need to manage. In turn, sufficient well-being of the family is necessary to guarantee adequate support and thus well-being for the person with PIMD. The purpose of this study was to examine the well-being of families with a child with PIMD, including possible differences between parents and siblings, and how individual and familial factors are related to FQOL. A total of 82 participants from 44 families with a child with PIMD in the Netherlands participated. Multilevel models were employed to analyze FQOL scores and which factors significantly affected scores. Families scored moderately high on both total score and subscales, scoring lowest on emotional well-being. There were significant differences between parents and siblings and a significant effect of age of the respondent on emotional well-being, material well-being, and disability-related support. Siblings scored higher than parents, and scores decreased with age on these domains. Although families with a child with PIMD scored, on average, satisfactory on their FQOL, they were least satisfied with the support for their emotional well-being, and may therefore require additional support for this aspect of their family life. Results of this study contribute to understanding the lives of families with a child with PIMD and their support needs.