In this chapter, we frame the media ecologies that contextualize the youth practices we describe in later chapters. By drawing from case studies that are delimited by locality, institutions, networked sites, and interest groups (see appendices), we have been able to map the contours of the varied social, technical, and cultural contexts that structure youth media engagement. This chapter introduces three genres of participation with new media that have emerged as overarching descriptive frameworks for understanding how youth new media practices are defi ned in relation and in opposition to one another. The genres of participation—hanging out, messing around, and geeking out—refl ect and are intertwined with young people’s practices, learning, and identity formation within these varied and dynamic media ecologies.