The aims of this project were to minimize organizational barriers and increase access to immunizations for children aged 6 months to 21 years in a multiethnic community health center in Honolulu. The intervention consisted of opening a "walk-in" shot clinic (WISC), run by a nurse practitioner, 2 evenings per week and Saturdays. Between January and July 2005, 351 clients accessed the clinic, with 774 immunizations administered. Clinic satisfaction measures were excellent. Up-to-date immunization status for all clients improved significantly. The WISC is an effective and customer-friendly way to improve childhood and adolescent immunization rates in a community health center setting.