This paper analyzes newly created samples of the 1910 and 1920 censuses of Puerto Rico to describe the composition and distribution of the island's households. It suggests, among other things, that Puerto Rican households were unusually large and complex --more so, in fact, than in all other documented Latin American or Caribbean cases. Household types, of which we recognize six in two main categories, varied greatly according to the race and gender of persons the census identified as their heads. The spatial distribution of households with black or mulatto heads suggests, moreover, a strong association between blackness in the early twentieth century and distinct settlement patterns characteristic of various earlier phases of island history, when enslaved Africans were among the predominant settlers. The study demonstrates a sharp rise in the proportion of nuclear households during the 1910s and suggests possible explanations based on the economic changes taking place in these years. Finally, it proposes ways to connect long-term socio-historical processes, such as those strengthening communal solidarities among rural dwellers, with certain household patterns visible in the early twentieth century. [ABSTRACT FROM AUTHOR]