This thesis examines the social and biological reproduction of households in the sectores populares, ie low income groups, both rural and urban, in the Meseta Central, yields specific outcomes at household level: the social formation based, originally, on smallholder coffee also depends on unusually successful domestic labour. Only multidisciplinary team work could adequately evaluate reproduction at the household level and establish the crucial role of the household in the wider economic system, as well as the role of women in maintaining diverse forms of subordination. The standard of living of the groups studied was estimated from the nutritional status of the children as a basic indicator of wellbeing; explanations of this status were sought in multivariate analysis of biological, economic, and social factors. Unexpectedly, the explanatory power of such variables such as income proved weak, the explanation appearing rather to lie with the less quantifiable social factors which rendered domestic labour more or less effective. Surveys and analysis, 1981-1984, sought to establish household survival strategies; diversified household enterprise proved of great importance in a survival constantly endangered by the insecurity of temporary, part-time and seasonal work so familiar in the Costa Rican economy as a whole. The household itself, as a flexible social organisation, seems one of the best resources for livelihood in the sectores populares, along with the ‘peasant' tradition of unpaid female and child labour. Proletarianisation remains incomplete. The economic categories of traditional Marxism prove inadequate to explain the gender subordination which characterises male female relations in countries of markedly uneven development, such as Costa Rica.