Much of the literature on charter schools treats them as an undifferentiated mass. Here we present and test a typology of charter schools that is grounded in the norms, traditions, and perspectives of the founding organization or organizers. We suggest that there are two broad categories of charter founders--those who are more mission oriented and those who are more market oriented--and we further disaggregate these categories into subtypes. Using data from a multistate survey of charter schools, we test the typology by examining charter school behaviors related to choosing a theme and targeting, deciding on the size and grade configuration, and marketing and market research behavior. (Contains 13 notes.)