Purpose -The purpose of this paper is to provide an overview of how social care staff experienced applying the Mental Capacity Act (MCA) 2005, following its implementation in 2007 in England and Wales. Design/methodology/approach -A longitudinal qualitative interview study explored the expectations, experiences and practice challenges of social workers and social care staff in relation to implementing the MCA for people with dementia. Findings -The MCA was widely welcomed, although more specific, fine-grained understandings were required. Updating and refresher training may be required, especially in settings where there is high staff turnover. Those in expert or advisory practice roles offer helpful detailed updating and legal digests to roll out to other staff. Research limitations/implications -Qualitative interviews are subjective and elucidate only what participants wish to cover. However, there were opportunities during this study for participants to be reflective and critical. Practical implications -Practitioners need initial and sustained continuing professional development. Access to expertise locally is welcomed. Originality/value -The MCA was implemented five years ago and is largely embedded in practice. The paper provides insight into the evolution of experiences, with suggestions of how to make implementation sustainable.