Since the early 1990s, UK social care policy has committed to supporting carers. Legislation (England and Wales) over this time period has recognised the importance of separate carer assessments that take into account an individual's ability and willingness to care. This paper considers carer assessment from the perspective of social care practitioners. It reports on qualitative data from a carer research programme that spans over 20 years (1993 to present) and includes 383 in-depth interviews with social care practitioners across England and Wales. Offering unique longitudinal insights, we identify some persistent tensions associated with the translation of UK carer assessment policy into social care practice. We explore practitioners' long-standing ambivalence towards carer assessment and their reluctance to evidence carer need via a separate assessment process. Deficits relating to the conduct of carer assessment are identified. For example, the reliance on structured, problem-focused assessment protocols that restrict discussions to the personal care aspects of caring and fail to capture the complex, diverse lives that carers lead. Carer assessments do not reflect the reciprocal nature of many caring relationships, as a one-way direction of care is assumed. They do not take into account the broader support network of individuals who may be involved in helping someone with complex care needs. Carer willingness to care continues to be taken for granted and planning for the future is a significant gap in carer assessment practice. The proposed changes to the social care systems across England and Wales provide a timely opportunity to review the process and conduct of carer assessment. Policy guidance needs to clarify the links between service user and carer assessments and the way these align within broader assessment and care management frameworks. Assessment tools that encourage a narrative approach to carer assessment and capture the affective aspects of care-giving could benefit future practice.