Cities in both developing and developed nations have long struggled with marginalized members of their population unable to access employment, education, and opportunities needed for social mobility. This limited access to opportunities transcends the globally acknowledged issue of urban inequality. Scholars refer to the phenomenon as social exclusion, involving the lack or denial of resources, rights, goods and services, and the inability to participate in the normal relationships and activities, available to the majority of people in society. Medellín, Colombia suffered from social exclusion for decades with drug cartels, gangs, and military groups leaving isolated communes entrenched in violence and poverty. However, the city has reinvented itself since the twenty-first century with innovation in public transportation and urban policy that have integrated these communes with the rest of the city, spurring growth and reducing violence. A study of Medellín’s transformation reveals the significance of mobility, social interventions, and the government’s collaboration with residents and the private sector in decreasing social exclusion. Medellín presents an example for other cities in need of engaging with their citizens to reduce marginalization and foster urban prosperity.