This comparative study of community organizations serving marginalized youth in New York City and Amsterdam utilized a novel ethnographic approach called reverse engineering to identify techniques for social change that are active in each organization, adaptable and translatable to other contexts. It found that youth-serving organizations led flexible responses to the crisis of COVID-19 as it affected those marginalized by race, immigrant status, housing instability, religion and gender. The organizations employed techniques that they had previously developed to cultivate youth well-being – among them connectivity, safe space, and creativity – to mount tailored responses to COVID-19 related crises. In New York City, these groups addressed crises of material survival resources (personal protective equipment, food, housing) whereas in Amsterdam, youth-serving organizations focused on social connections and emotional well-being as the government met more of participants’ material needs.