OBJECTIVES: Although blood pressure (BP) is routinely measured in outpatient visits, elevated BP and hypertension are often not recognized. We evaluated whether an electronic health record linked clinical decision support (CDS) tool could improve the recognition and management of hypertension in adolescents. METHODS: We randomly assigned 20 primary care clinics within an integrated care system to CDS or usual care. At intervention sites, the CDS displayed BPs and percentiles, identified incident hypertension on the basis of current or previous BPs, and offered tailored order sets. The recognition of hypertension was identified by an automated review of diagnoses and problem lists and a manual review of clinical notes, antihypertensive medication prescriptions, and diagnostic testing. Generalized linear mixed models were used to test the effect of the intervention. RESULTS: Among 31 579 patients 10 to 17 years old with a clinic visit over a 2-year period, 522 (1.7%) had incident hypertension. Within 6 months of meeting criteria, providers recognized hypertension in 54.9% of patients in CDS clinics and 21.3% of patients in usual care (P ≤.001). Clinical recognition was most often achieved through visit diagnoses or documentation in the clinical note. Within 6 months of developing incident hypertension, 17.1% of CDS subjects were referred to dieticians or weight loss or exercise programs, and 9.4% had additional hypertension workup versus 3.9% and 4.2%, respectively (P = .001 and .046, respectively). Only 1% of patients were prescribed an antihypertensive medication within 6 months of developing hypertension. CONCLUSIONS: The CDS had a significant, beneficial effect on the recognition of hypertension, with a moderate increase in guideline-adherent management.