Failure to thrive (FTT) is a common symptom leading to hospitalization of children. Most literature describing this population is from 30 years ago. Since that time the hospitalized population has become more medically complex. We aimed to describe children hospitalized for FTT in a tertiary care pediatric hospital. We prospectively collected demographic, anthropometric, evaluation, and outcome data for 92 consecutive children admitted with FTT. The majority of children grew with behavioral interventions alone (primary nonorganic FTT) and had negative evaluation (n = 63). Children with primary organic FTT had longer hospital stays (7 vs 4 days; P <.001) and lower daily weight gain (35 vs 58 g/d; P <.001). Laboratory, radiological, and endoscopic evaluation rarely led to a diagnostic etiology of FTT in hospitalized children. We conclude that children hospitalized with FTT should be observed for weight gain prior to pursuing diagnostic investigation.