Background: Internationally, nursing professionals are coming under increasing pressure to highlight the contribution they make to health care and patient outcomes. Despite this, difficulties exist in the provision of quality information aimed at describing nursing work in sufficient detail. The Irish Minimum Data Set for General Nursing is a new nursing data collection system aimed at highlighting the contribution of nursing to patient care. Objectives: The objectives of this study were to investigate the construct validity and internal reliability of the Irish Nursing Minimum Data Set for General Nursing and to assess its usefulness in measuring the mediating effects of nursing interventions on patient well-being for a group of short stay medical and surgical patients. Design: This was a quantitative study using a repeated measures design. Setting: Participants sampled came from both general surgery and general medicine wards in 6 hospitals throughout the Republic of Ireland. Participants: Nurses took on the role of data collectors. Nurses participating in the study were qualified, registered nurses engaged in direct patient care. Because the unit of analysis for this study was the patient day, patient numbers were considered in estimations of sample size requirements. A total of 337 usable Nursing Minimum Data Set booklets were collected. Methods: The construct validity of the tool was established using exploratory factor analysis with a Promax rotation and Maximum Likelihood extraction. Internal reliability was established using the Cronbach's Alpha coefficient. Path analysis was used to assess the mediating effects of nursing interventions on patient well-being. Results: The results of the exploratory factor analysis and path analysis met the criteria for an appropriate model fit. All Cronbach Alpha scores were above 7. Conclusion: The overall findings of the study inferred that the Irish Nursing Minimum Data for General Nursing possessed construct validity and internal reliability. The study results also inferred the potential of the tool in the investigation of the impact of nursing on patient well-being. As such, this new tool demonstrated potential to be used in the provision of quality information to inform policy in relation to the organisation of nursing care. More research is needed to further establish its use in the assessment of patient outcomes. © 2013 Elsevier Ltd.