The invention relates to systems and methods for behavioral modification of users in an online community where users store or share data to help one another reach informed decisions. One aspect of the invention provides a method for encouraging active participation in an online community. The method includes: receiving information from a first user regarding a topic, receiving a request from a second user for additional information desired from the first user, and sending a personalized message to the first user requesting the additional information. Another aspect of the invention provides a computer-readable medium whose contents cause a computer to perform a method for encouraging active participation in an online community. The method includes: receiving information from a first user regarding a topic; identifying additional information desired from the first user; and sending a personalized message to the first user requesting the additional information.