The relationship between energy intake and growth rates in height and weight was investigated in 190 Guatemalan children. Intake of a protein-energy, but not of an energy supplement, was significantly related to growth. However, the effect per calorie was similar for both types of supplements. Further, when the sample was pooled, the above relationship was not altered by the presence of protein in the supplement nor by sex, home dietary intake, morbidity and socioeconomic status. Therefore, the effect observed was probably due to energy. This was congruent with analyses of the home dietary intakes which showed energy, but not protein, to be limiting. Home energy intake, though in the expected direction, was not significantly related to growth, the effect per home diet calorie being several times smaller than that per supplement calorie. It is hypothesized that this was due to poor reliability and bias in individual dietary estimates. © 1978, Taylor & Francis Group, LLC. All rights reserved.