RESUMEN
Since the early Chicago School, urban researchers have used residential proximity to assess contacts within and between racial and ethnic groups. This approach is increasingly limited. Diverse groups use email, social networking sites, instant messaging and mobile phones to communicate across urban zones and distant cities. These practices enable mutual support among far-flung family members and co-ethnics as they engage with an array of institutions throughout their day. Through interviews and observations that include women and men of diverse occupations, races and national origins, the author explores how and why cross-place enclosures of sociality and resources develop. Rather than framing the residential area as the locus of racial/ethnic concentration, the author focuses on cross-place concentrations in the technologically mediated workspace. This study enhances theorization of the structural negotiations, interpersonal pressures and group preferences that produce separate lifeworlds in globalizing cities.