The experiences of mothers of adult offspring with a dual diagnosis have rarely been discussed in the literature, despite growing involvement and responsibility of mothers for daily care of their children. Interpretive phenomenological analysis of in-depth interviews was used to examine the mothering experience of 12 mothers of adult offspring with dual diagnosis. The analysis revealed that the mothers' experiences were intensive, abusive, and isolating, and simultaneously rendered them invisible, undervalued, or ignored by professionals, community, and family. Furthermore, the analysis indicated that this experience of 'intensive-invisible' mothering was promoted or prevented by three intersecting mechanisms, identified here as discursive, institutional, and spatial. The research contributes to the fields of knowledge regarding family members of people with mental health problems, by adding a theoretical layer that takes into account how public discourses of motherhood mould women's accounts of their mothering experience. Practical implications of these findings for professionals working with these mothers are discussed. Specifically, therapeutic intervention that focuses on identifying and modifying the underlying psychological and social processes associated with the 'intensive-invisible' mothering experience could be useful.