Fast growth rate in broilers comes with welfare concerns and research is needed to determine if fast- and slow-growing broilers differ in pathogen resistance. The objective of this study was to evaluate differences in fast- (FG) and slow-growing (SG) broilers when challenged with Salmonella Typhimurium or broth (control) 14 days post-hatch. Plasma IgA and IgG, jejunum and ileum histomorphology, and behaviors were measured. FG had greater d12 and d24 body weight and d7 jejunum measures, indicating better absorption, and earlier increases in plasma IgA and IgG, indicating earlier immune development. SG had greater d7 IgG, indicating stronger maternal immunity. Post-challenge, FG gut morphology was more impaired, and SG had greater IgA and reduced sham foraging, indicating a stronger immune response to challenge. The results illustrate fast- and slow-growing broilers differ in Salmonella resistance, which can help breeders make selection decisions to prevent Salmonella transmission into the human food supply.