Since publication of the recommended childhood immunization schedule in July 1996, the Advisory Committee on Immunization Practices (ACIP), the American Academy of Pediatrics (AAP), and the American Academy of Family Physicians (AAFP) have made important changes in recommendations for preventing pertussis and poliomyelitis. Following the licensure of two acellular pertussis vaccines for infants, the advisory groups now recommend use of acellular pertussis vaccine (Tripedia or ACEL-IMUNE) as the preferred vaccine for pertussis vaccination for infants beginning at age 2 months. To reduce the risk for vaccine-associated paralytic poliomyelitis (VAPP), recommendations for poliovirus vaccination have expanded the use of inactivated poliovirus vaccine (IPV) by providing three options for poliovirus vaccination (sequential IPV/oral poliovirus vaccine [OPV], all IPV, or all OPV). In addition, a combination Haemophilus influenzae type b (Hib) and hepatitis B vaccine and a combination diphtheria and tetanus toxoids and acellular pertussis vaccine (DTaP) and Hib vaccine have been licensed for use in certain situations. This report presents the recommended childhood immunization schedule for 1997 and explains the changes that have occurred since the last publication of the schedule.