Abstract: Systems and methods are disclosed for targeting effective contributors and identifying high quality contributions. For example, a method may include displaying an advertisement to a potential contributor via an advertising platform, receiving an indication that the potential contributor responded to the advertisement, generating a crowdsourcing exercise that is presented to the contributor, receiving a response (a conversion event) from the contributor to the crowdsourcing exercise, and notifying the advertising platform about the conversion event. As another example, a method may include determining a concept space for a new contribution, obtaining previously correct and incorrect contributions of the contributor in the concept space, and determining an expertise confidence score for the new contribution based on a comparison of the new contribution with the previously correct and incorrect contributions.