A rapid survey was conducted to describe the immunization status of the 0- to 2-year-old population in selected communities of Kern County, California, and identify reasons for noncompliance with immunization recommendations. Households were selected by two-stage cluster sampling. Among 860 children, 38% had received immunizations on schedule, while 44% had not received the recommended doses for their age. Compliance with the immunization schedule worsened dramatically after the first year of life. Among 2 year olds, the proportion that had the recommended number of vaccine doses was 81% for MMR, 82% for polio, 65% for DTP, and 47% for Hib. Parents' main reasons for noncompliance included child's illness, procrastination, and limited access to information and services. The low levels of compliance reflect lack of active follow-up in preventive health care across socioeconomic levels. The results show the importance of aiming immunization messages at parents and physicians of 12- to 18-month-old children. The rapid survey approach offers public health agencies an efficient means of assessing community health problems and targeting programs according to need.