OBJECTIVES: We sought to determine the time to pathogen detection in blood and cerebrospinal fluid (CSF) for infants =60 days old with bacteremia and/or bacterial meningitis and to explore whether time to pathogen detection differed for non-ill-appearing and ill-appearing infants. METHODS: We included infants =60 days old with bacteremia and/or bacterial meningitis evaluated in the emergency departments of 10 children's hospitals between July 1, 2011, and June 30, 2016. The microbiology laboratories at each site were queried to identify infants in whom a bacterial pathogen was isolated from blood and/or CSF. Medical records were then reviewed to confirm the presence of a pathogen and to extract demographic characteristics, clinical appearance, and the time to pathogen detection. RESULTS: Among 360 infants with bacteremia, 316 (87.8%) pathogens were detected within 24 hours and 343 (95.3%) within 36 hours. A lower proportion of non-ill-appearing infants with bacteremia had a pathogen detected on blood culture within 24 hours compared with ill-appearing infants (85.0% vs 92.9%, respectively; P = .03). Among 62 infants with bacterial meningitis, 55 (88.7%) pathogens were detected within 24 hours and 59 (95.2%) were detected within 36 hours, with no difference based on ill appearance. CONCLUSIONS: Among infants =60 days old with bacteremia and/or bacterial meningitis, pathogens were commonly identified from blood or CSF within 24 and 36 hours. However, clinicians must weigh the potential for missed bacteremia in non-ill-appearing infants discharged within 24 hours against the overall low prevalence of infection.