Content generation is a critical aspect of user engagement in online communities, yet many platforms face a problem of under-provision. We focus here on the potential of different types of incentives (descriptive social norms and money) to stimulate the production of online reviews. Partnering with a Chinese online clothing retailer, we conducted a large-scale randomized field experiment, in which we considered the independent and joint effects of monetary payment and descriptive social norms on the quantity and quality of reviews. We found that money attracts a greater volume of reviews, descriptive social norms attract greater quality, and combining the two yields the greatest benefit in both respects. We discuss the mechanisms underlying these effects as well as the implications of our results for theory and practice. We also highlight potentially fruitful avenues of future research.