Online content and service providers find it challenging to elicit payment from their users and thus face a financial sustainability challenge. We follow past research that showed that the use of feedback surveys may lead to consumer loyalty and study whether simple ‘calls to action’—prompts that require the user to rate the content or service—encourage monetary conversion. We first present controlled web experiments to establish a causal relationship between users’ exposure to prompts and their subsequent monetary contributions. Study participants watched videos on a video website and were presented with prompts to rate the current video. Users who were prompted to rate videos donated more money to the website compared with users who were not exposed to prompts. Notably, the prompts did not affect users' satisfaction. Next, in two large-scale field studies, conducted in collaboration with a major publishing website, we establish the applicability of our findings to real-life settings. Specifically, we show that users who are prompted to rate their experience become significantly more likely to convert to a paid version. Our research is novel in showing, both in the lab and in the field, a causal relation between calls to action and user conversion.