Although the prevalence of malnutrition in developing countries is decreasing, it is still a major problem for many children under five. As socio-economic conditions are the main determinants, a final solution for this problem can only be envisaged in the long run. Still, short-term strategies need to be defined in order to relieve the sufferings of individual children and their families. Understanding the problem and consequently formulating intervention programs at the local level remains a complex and difficult issue. The first reason being that the process of malnutrition expresses itself in different forms and with variable consequences. A second reason making malnutrition a complex problem is that the primary causes -- the interaction between insufficient food supply and the frequent recurrence of infectious diseases -- are determined by a multitude of factors of different natures. This complexity -- of its expressions, effects, and causality -- makes it difficult to get a global vision and understanding of the problem, which clearly impedes the definition of rational and integrated intervention strategies. Nevertheless, a better understanding of the pathophysiology of malnutrition and of the factors that influence the growth process in preschool age, will help to better direct actions. To this effect, a conceptual model will be built, based on recent insight in the process of malnutrition within this age group. From this model, two lines of action for increasing the chances of preschool children to express their initial growth potential, become apparent. A first series of activities could tackle the process that, via wasting and recurrence of infections, leads to an increased mortality risk. As timely intervention reduces the risk of depletion of energy reserves, these activities would also have an indirect impact on physical development. Elaborating strategies for secondary prevention and for treating severe cases belongs to the specific competence of the health sector. In the second line of action, the aim is to intervene before reserves are depleted. Here, primary prevention and health promotion are choice activities. This frame of reference will be used for analysing existing health programs for preschool children and how they propose to improve the management of malnutrition. This analysis will show that primary health care services can play a much more important role than usually attributed to them. Identifying these gaps and elaborating alternatives is the purpose of this article.