An increasing number of people live with chronic disease or multi-morbidity. Current consensus is that their care requires an integrated model bringing different professionals together to provide person-centred care. Although primary care has a central role in managing chronic disease, and integration may be important in strengthening this role, previous research has shown insufficient attention to the relationships between primary care and integration. This review summarizes primary care involvement in integrated care interventions and assesses the effect of those interventions on a range of measures of primary care functions and wider outcomes.