Growth faltering, previously known as failure to thrive, is a broad term describing children who do not reach their expected weight, length, or body mass index for age. Growth is assessed with standardized World Health Organization charts for children younger than two years and Centers for Disease Control and Prevention charts for children two years and older. Traditional criteria for growth faltering can be imprecise and difficult to track over time; therefore, use of anthropometric z scores are now recommended. These scores can be calculated with a single set of measurements to assess malnutrition severity. Inadequate caloric intake, the most common cause of growth faltering, is identified with a detailed feeding history and physical examination. Diagnostic testing is reserved for those who have severe malnutrition or symptoms concerning for high-risk conditions, or if initial treatment fails. In older children or those with comorbidities, it is important to screen for underlying eating disorders (e.g., avoidant/restrictive food intake disorder, anorexia nervosa, bulimia). Growth faltering can usually be managed by the primary care physician. If comorbid disease is identified, a multidisciplinary team (e.g., nutritionist, psychologist, pediatric subspecialists) may be beneficial. Failure to recognize and treat growth faltering in the first two years of life may result in decreased adult height and cognitive potential.