Failure to thrive (FTT) refers to inadequate weight gain in children, defined by weight below the 5th percentile, a drop of more than 2 percentile lines, or less than 80% median weight for height. Diagnosis requires thorough history and physical examination due to multiple potential causes. Hospitalization may be necessary for severe malnutrition, underlying conditions, or failed outpatient treatment. Early recognition and treatment are critical to prevent developmental delays and long-term complications. Since FTT often stems from inadequate caloric intake rather than organic disease, an interprofessional approach involving nutrition specialists, behavioral health professionals, and social workers is essential for effective management.