Although Occupy has received extensive media and scholarly attention, there has not yet been systematic research on its activists' recruitment pathways and modes of participation. In this article, we focus on the mobilization success (Staggenborg 1995) of Occupy and adopt the concepts of 'free space' and 'modes of association' (Polletta 1999) to understand how individuals came to participate in Occupy. We consider biographical and structural availability and make distinctions between those more or less involved. By drawing on qualitative and quantitative data gathered in November and December 2011 in London we find that Occupy activists take a range of pathways into differential forms of involvement (more or less visible or time-consuming, ...