Background Initiatives are needed to promote and evaluate clinical pharmacy. In this context, benchmarking could be useful. Objective To develop and validate a benchmarking tool for clinical pharmacy activities. Setting Six Belgian hospitals. Method A narrative literature review and two focus groups were performed to identify (1) clinical pharmacy benchmarking projects, (2) clinical pharmacy activities with a proven positive impact on the quality of care for patients, (3) quality indicators and (4) contextual factors to be included in the tool. Next, a Delphi survey and a test of the tool in practice led to content validation and usability of the benchmarking tool. Main Outcome Measure To identify quality indicators and contextual factors to be included in the tool. Results Three Delphi rounds were required (rounds 1-2: 9 participants, round 3: 8 participants). Ten quality indicators and 36 relevant contextual factors were selected. These 10 quality indicators represent 6 clinical pharmacy activities that demonstrated to improve patient outcomes: medication reconciliation at admission, patient monitoring, information provided to the health care team, patient education, discharge and transfer medication counselling, and adverse drug reaction monitoring. To collect the information needed to compose the quality indicators and to benchmark, the tool consists of three data collection instruments. An instruction manual accompanies the tool. Conclusion We have developed and validated a benchmarking tool, designed to identify and promote clinical pharmacy activities that demonstrated to improve patient outcomes. Future perspectives include the use of the tool on a national scale to identify the most efficient practices and their enablers and barriers.