Background.Increasing therapeutic inpatient activities may improve the quality and outcomes of care. Evaluation of these interventions is necessary including assessment of cost-effectiveness. The aim of this paper is to describe the development and reliability of a tool to collect information on care contacts and therapeutic activities of patients on inpatient wards.Method.The development of the tool consisted of: 1) literature review, 2) interviews with staff, 3) expert consultation, 4) feasibility study, 5) focus groups with staff members, and 6) reliability tests. Service use data were collected with the tool and costs calculated.Results.Service users' reported more use of activities than that contained in case notes during a 7-day period. This resulted in a cost difference of £10 per person. Case notes had more one-to-one nursing contacts, with a cost difference of £4 per person. One-day data showed less nurse contact time reported by participants compared to observational data (p < 0.001) but similar use of activities. Costs were £46 for the tool and £67 for the observational data.Conclusions.This tool is a good source of information on the number of activities attended by service users and contacts with psychiatrists. There is some disagreement with other sources of information on interactions between service users and nurses, possibly reflecting different definitions of a ‘meaningful contact’. This does not have a major impact on cost given that for much of the care received there is reasonable agreement.