Through stories of young girls at play produced in a collective biography workshop we trace flows of desire and excesses of joy, and bring recent feminist work on positive affect into our analysis of girlhood becomings. Ringrose (2011, 2013) argues that the concept of the “affective assemblage“ brings together affect, embodiment, and relationality in powerful ways to enable a mapping of how desire moves through the social. She suggests that the affective capacities of assemblages can be “life affirming or life destroying“ (2011: 602). In this article we are interested in mapping flows of desire, moments of joy and possibility in moments of girlhood, and in the limitations and contingencies within these moments that shut down these possibilities. We suggest that the methodology of collective biography (Davies and Gannon 2006, 2009, 2013) offers potential for tracing the microparticulars of girlhood becomings.