Non-profit organizations' (NPO) utilization of social media has received attention from researchers in many fields. However, little research studies how legal recognition affects NPOs' ways of using social media or how, specifically, usage differs among social media platforms. As part of a larger study of NPO social media use, in this poster, we explore and analyze how formal and informal NPOs use Facebook and Twitter, and discuss how the different patterns of use that emerge result from NPOs' strategic choices.