La Perla, Puerto Rico’s most famous “slum,” developed since the early 1900s outside the walls of Old San Juan, the historic Old Town of the Puerto Rican capital. By the mid-twentieth century, La Perla was a symbol of the poverty and deprivation that development and scientifically informed planning attempted to resolve. It became the subject of various improvement plans with varying degrees of
inhabitant participation. Comparing building types, ownership structures, and municipal policies throughout La Perla’s history, this chapter questions the validity of the formal-informal distinction
that is fundamental in recent literature on “slums,” and engrained in development and modernization ideologies. In terms of architecture, planning, and legal situation, the neighborhood has been
characterized by a combination of formal and informal elements. There was both self-help construction and profit-driven development, stable and improvised buildings, unequal power relations, and strong economic ties to the rest of the city.