This chapter focuses on the challenges faced in considering how and when to evolve the foundational Eurogang definition of gang membership and the potential pathways forward. Changes in the gang landscape over the last decade at the Eurogang Workshops have prompted discussions about whether or not it is reasonable to adapt the Eurogang definition, or the survey instrument, to be able to capture these shifts. The principal issues that have been discussed include: the proliferation of gang activity online and across social media and how that impacts the street-oriented nature of gangs; the need to capture non-traditional youth gangs that should, but are implicitly or explicitly left out of traditional street gang studies (e.g., White power/alt-right gangs); and how to capture the churning of gang members in and out of correctional systems (i.e., prison gangs/security threat groups). This chapter will overview the benefits and drawbacks that were discussed when considering the different ways of capturing these changes, including modifying the definition itself, adapting the survey instrument, or both. The chapter is aimed at bringing attention to the methodological, philosophical, and practical implications of modifying the long-standing and highly utilized Eurogang definition and survey instrument.