The study was conducted to assess the factors affecting undernutrition in undernourished children in a selected elementary school in Laguna. The researchers aimed to determine the relationship between the causes of undernutrition and the demographic profile of the respondents. Among the 729 students in the school, 51 children were undernourished, according to the list given by their nutrition office. The researchers found that most of the undernourished children were male, and the age where undernutrition occurred most was 5 years of age. The socioeconomic status directly affects the diet and lifestyle of the respondents. The study was done by the researchers to have better knowledge and understanding of the occurrence of undernutrition in the said community. This research provided relevant information and data for further implementation of effective actions to this issue.