Currently available tools to measure teamwork, an essential component of primary care, are generally very resource intensive and thus cannot be administered frequently. To explore the possibility of developing a brief teamwork-assessment instrument, we first administered 29 questions about teamwork from the Practice Environment Checklist (PEC) to all members of six clinical teams in a residency outpatient practice (n=56). We found that the scale assessed a single dimension of teamwork and that a five item survey has acceptable reliability (Cronbach alpha=0.89). In a subsequent validation study among an expanded sample of clinic staff (n=89), we found that the five-item questionnaire could be completed in less than 3 minutes. It continued to have an acceptable internal consistency (Cronbach alpha=0.82) and that all five items had sizeable item-total correlations. The resulting short form of the PEC may be useful for frequent assessment of team function.