Dementia continues to be under-recognized, an important issue in many countries. Policy addressing this has focused on the role of general practice-based staff, but dementia represents an area in which closer collaboration between community health and social services can reap benefits. This study examined the impact of a national policy in England, the Single Assessment Process (SAP), introduced across these agencies from April 2004, aimed at improving assessments by the use of shared procedures and assessment tools. Impact was measured in terms of the reliability by which dementia, and associated conditions, were identified and correctly detected in one area’s statutory community care assessments. Recognition of dementia, grooming, toileting and incontinence difficulties were significantly improved after the policy. Depression was an exception. Existing communication difficulties made it more likely that dementia would be identified and correctly recognized. Findings are discussed in terms of more closely involving care managers in detecting dementia.