There is an ongoing need to support high-quality research publications that requires a greater emphasis on the role of the peer review process. The difficulties faced by editors in finding committed reviewers and in avoiding delayed review reports, as well as the frequency of failure in manuscript error detection, all stress the need to identify incentive strategies that will ensure high-quality peer reviews. Based on a qualitative approach, this paper explores referees' decision frames when reviewing, the characteristics of the review behaviour, and the associated benefits and costs. Semi-structured interviews were conducted with 42 journal referees. The results highlight the motivating factors that affect the decision to review, or not to review. Two motivation frames-of-reference were identified: that of a prospective member of the scientific community focused on self-achievement vs. that of a member of the scientific community focused on the group. Different situational cues activate a particular frame: the match between reviewer's expertise and the manuscript topic, the identification with the scientific community, and the quality of the journal. The findings suggest strategies able to minimize referees' perceived costs when reviewing. This research sheds new light on the strategies that have the potential to boost the peer review process.