Loyalty programmes (LPs) have increased in number and popularity, but their effects on customer behaviour remain equivocal, due to a lack of understanding of the drivers of LP effectiveness and insufficient generalizable conclusions across prior studies. This paper synthesizes current knowledge pertaining to LPs, reconciles opposing findings by exploring the conditions that mediate and moderate the effects of LP participation on consumer responses, and charts important avenues for research. Overall, we find that LPs are effective in increasing consumer purchase behaviours over time, but the impact differs across consumer segments and markets. Currently, neither firms nor consumers fully benefit from the opportunities that LPs offer. To that end, we identify aspects which help researchers and practitioners increase their understanding of LP benefits and pitfalls. Through this study, companies that already have LPs will be able to improve their performance, and those that are about to introduce one will better understand the implications of the LP launch.