In this study, we estimate the effect of “online following,” a basic form of online social interaction, on members’ contributions in open source software (OSS) communities, using a unique longitudinal data set containing information on over 4 million OSS developers and their social interactions over 7 years. We find that obtaining new followers in the previous month has a significant positive effect on developers’ level of contribution in the current month. The effect carries over to the next month although the marginal effect decreases. We further find that the effect of new followers on their contribution level is much stronger for freelancers than those with company affiliation. In contrast to the previous literature that posited the existence of non-monetary incentives for developers who contribute to the OSS communities, our result suggests the existence of incentives that are tied to future monetary rewards for developers on these platforms. Our findings have important implications for the OSS platforms as well as the OSS community. OSS platform designers may consult our results to learn about the social features that affect members’ contribution. We also encourage OSS community to use the “following” feature more prominently on OSS platforms to incentivize higher contribution levels to the projects.