Purpose – This paper seeks to develop a self-report instrument completed by team members, the Integral Team Effectiveness Measure (ITEM), in order to assess team strengths and weaknesses based on a review of research and models of effective teams. The ability of the instrument, based on an “integral” or holistic framework, to capture a latent factor relevant to team success is tested. Based on two studies, support for the construct and predictive validity of the ITEM measure is provided.Design/methodology/approach – Psychometric evaluation of a survey instrument is described. A quasi-experiment to see whether an objective measure of team performance can be predicted from the instrument and multi-level modelling was also incorporated.Findings – Although there are many elements necessary for good teamwork, there is nevertheless an underlying common theme. This underlying theme or construct of integral team effectiveness can be measured with a self-report instrument, which successfully predicted subsequent team performance in a sample of 45 teams.Practical implications – The Integral Team Effectiveness Measure (ITEM) is an instrument that captures an important underlying quality of teams. Organisations relying on teams may benefit from using the ITEM to diagnose weaknesses and to design corrective interventions.Originality/value – Although many previous studies have described variables which impact team performance, integral team effectiveness is an original contribution in that it describes and measures an underlying essence of teamwork. Managers and team members may find integral team effectiveness valuable for overcoming the apparent complexities and contradictions that confound sincere efforts to improve team performance.