User-contributed content as an input to the production of information services is not new, but it is growing rapidly in significance and prevalence. Open-source software, Wikipedia, and Flickr are but a few examples of the variety of information products and services relying on user-contributed content. I propose a characterization of user-contributed content, and identify contributor behavior issues critical for success. From the perspective of an information service provider, or the economy as a whole, these issues predict underprovision of content, inefficient mixes of quality and variety, and undesirable levels of content pollution. How might we design information services or systems to ameliorate these problems? Given the centrality of autonomous, motivated human behavior in user-contributed content problems, I argue this is a problem for \emph{incentive-centered design}: how to configure economic, social and psychological incentives to induce contribution, discourage pollution, and motivate sufficient effort to generate quality? To illustrate, for a content pollution problem loosely based on a popular Web site's experience, I offer a stylized mechanism that relies on user-contributed (meta)content to screen out polluting contributions.http://deepblue.lib.umich.edu/bitstream/2027.42/78183/1/sea-icd4ucc.pdf