Since April 2003, all adults requiring social care services must have an assessment to determine their eligibility, which is set within the four-level framework of Fair Access to Care Services [FACS; LAC (2002)13]. This paper examines the implementation of FACS by community mental health teams in eight sites in mental health partnership trusts, and one in a mental health and social care trust in the UK. Twenty-eight respondents (managers within trusts and social services departments) participated in in-depth qualitative interviews, which were undertaken between August 2004 and February 2005. The interviews covered: consultation with users and partner organisations; training and briefings for staff; FACS thresholds; integration of FACS and the Care Programme Approach; and the impact of implementing FACS on budgetary arrangements between health and social care. Using the framework analysis approach to analyse data, it was found that FACS implementation in mental health services has been somewhat haphazard, and has identified real differences between health and social care approaches to eligibility determination, assessment and priorities. In particular, the type and amount of consultation, training and induction into FACS was variable, and in some cases, unacceptably poor. While FACS may have reduced variability between authorities, the exercise of professional judgement in the operation of FACS and the lack of high-quality preventative services remain as potential sources of inequity within the system. The authors conclude that FACS has revealed and reinforced a growing separation rather than an integration of mental health and social care ideas and practices, at least in the participating sites.