THE CLINICAL EVALUATION of febrile infants younger than 3 months has been the subject of much study and controversy.1-8 Important areas of needed investigation in this age group include (1) the pursuit of the most useful laboratory tests for evaluating ill and/or febrile neonates, who are frequently already hospitalized, at risk for early neonatal sepsis, typically occurring in the first week of life, and (2) determining the utility of obtaining spinal fluid samples from lumbar punctures in febrile 1- to 3-month-old outpatients who do not appear ill but are at risk for late neonatal sepsis and/or bacterial meningitis. These 2 questions are distinct and involve different clinical scenarios and patient subpopulations in the first 90 days of life.