In the years since a symposium on science and ignorance at the 1993 annual meeting of the American Association for the Advancement of Science (AAAS), a small but growing number of scholars has begun to study scientific ignorance. This essay offers informal descriptions of three major projects on the social construction of ignorance and raises the possibility for the development of a sociology of scientific ignorance (SSI) to complement the existing sociology of scientific knowledge (SSK). As currently conceptualized, SSI would draw attention to a wide range of phenomena in scientific discourse and practice; these include a rich assortment of ignorance claims, and ignorance arrangements, social arrangements that work to deprive people of scientific knowledge. For SSI to develop its full potential will require scholars to overcome ignorance of existing scholarship and resistance within both science and science studies to ignorance as an organizing idea. The benefits, if scholars can do these things, may be many.