Background: A national health survey in Indonesia conducted in 2013 showed that the prevalence of anemia in school-aged children and adolescents tripled from a survey conducted in 2007. Children and adolescents are particularly susceptible to iron deficiency anemia (IDA) and iron deficiency (ID) because of their rapid growth and puberty. Teenage girls are at risk because of their menstrual bleeding. Low socioeconomic status in children and adolescents is also a strong risk factor for experiencing iron defi­ciency. Studies regarding the prevalence of ID and IDA in Indonesia still vary and are lacking. This study aims to describe the prevalence of anemia in children and adolescents with low socioeconomic conditions. Methods: This is a cross-sectional study conducted at two schools in the suburbs of Jakarta on children and adolescents aged 6–18 years old. Personal data and laboratory identities (complete peripheral blood count, reticulocyte hemoglobin content, ferritin, transferrin saturation, and C-reactive protein) were collected to determine iron status. Analysis was performed using SPSS program version 22.0. Results: The overall prevalence of anemia was 14.0%. The prevalence of IDA, ID without anemia, and iron depletion was 5.8%, 18.4%, and 4.3%, respectively. The prevalence of IDA, ID, and iron depletion was higher in females than in males. Conclusion: The overall prevalence of anemia in children and adolescents is lower than the national data. Special consideration needs to be taken for the female population, who are more at risk of developing ID and IDA.