A social networking system presents questions to a user on an interface associated with the social networking system to elicit information about the user that is missing from the user's profile or is otherwise outdated. The questions are selected based on a number of factors, such as the need for or value of the information item, probability of a response, or cost of collecting the information item. In presenting the selected question, the social networking system prompts a user for information about the user in a an interface associated with a page from the social networking system, an application external to the social networking system, or using a push notification or prompt. The questions may be formatted in various ways, such as an explicit question, confirmation, a selection of responses, or social context to encourage the user to respond to the question.