  Many undergraduate and graduate physics students participate in some form of
public engagement throughout the course of their studies, often through groups
supported by physics departments and universities. These informal teaching and
learning programs can offer unique opportunities for physics identity
development. Understanding how physics identities can be fostered will allow us
to work toward a field that is inclusive of more identities. In this study, we
build on previous work to investigate student-facilitator experiences in three
informal physics programs using an operationalized Communities of Practice
framework. Through our analysis, we identify different structures within these
programs that support physics identity development.
