Illness Acute Respiratory Infections (ARI) especially pneumonia is a major health problem in toddlers in Indonesia because it is still a cause of morbidity, infant mortality and under-fives so that WHO calls it pneumonia is the leading killer of children worldwide but not much attention to this disease so pneumonia is called also a forgotten toddler killer or the forgotten killer of children. This study aims to determine the relationship between low birth weight, immunization status, feeding pattern, level of mother’s knowledge and the presence of smokers in the home on the incidence of pneumonia in infants in the work area of Kamonji Public Health Center, Palu City. The type of research used is analytical survey research with a cross sectional approach. The number of samples was 188 respondents. Data were analyzed by univariate and bivariate, at 95% confidence level (ρ <0.05). The results of the Chi-Square test showed that the history of LBW, immunization status, feeding pattern, level of mother’s knowledge, and the presence of smokers in the home were associated with the incidence of pneumonia in infants with a value of ρ <0.05. Kamonji Public Health Center is expected to provide health services through promotive and preventive efforts that aim to increase mother’s knowledge about the practice of preventing pneumonia in toddlers, besides that an active role in early detection and management of pneumonia is needed between health workers and all mother’s toddler so that coverage of case discovery pneumonia can increase.