High blood pressure in children and adolescents is a growing health problem that is often overlooked. Children should be screened for elevated blood pressure annually beginning at three years of age or at every visit if risk factors are present. In children younger than 13 years, elevated blood pressure is defined as blood pressure in the 90th percentile or higher for age, height, and sex, and hypertension is defined as blood pressure in the 95th percentile or higher. In adolescents 13 years and older, elevated blood pressure is defined as blood pressure of 120 to 129 mm Hg systolic and less than 80 mm Hg diastolic, and hypertension is defined as blood pressure of 130/80 mm Hg or higher. Ambulatory blood pressure monitoring should be performed to confirm hypertension in children and adolescents. Primary hypertension is now the most common cause of hypertension in children and adolescents. A history and physical examination and targeted screening tests should be done to evaluate for underlying medical disorders, and children and adolescents with hypertension should be screened for comorbid cardiovascular diseases, including diabetes mellitus and hyperlipidemia. Hypertension in children is initially treated with lifestyle changes such as weight loss if overweight or obese, a healthy diet, and regular exercise. Children with symptomatic hypertension (e.g., headaches, cognitive changes), stage 2 hypertension without a modifiable factor such as obesity, evidence of left ventricular hypertrophy on echocardiography, any stage of hypertension associated with chronic kidney disease or diabetes, or persistent hypertension despite a trial of lifestyle modifications require antihypertensive medications and should be evaluated for cardiovascular damage with echocardiography. Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, calcium channel blockers, and thiazide diuretics are effective, safe, and well-tolerated in children.