This study was undertaken to characterize the mucosal response to Cryptosporidium parvum in infected calves that had recovered from diarrhea. Flow cytometric surface phenotypes of lamina propria lymphocyte (LPL) suspensions from infected calves and age-matched controls revealed the presence of a significantly larger proportion of CD25 LPL in infected calves than in controls. Freshly isolated LPL from infected calves expressed more iNOS and interferon (IFN)-γ than did controls. Infected calves excreted IgG₁ and IgG₂ isotype antibodies to C. parvum p23 by the end of the experiment. Moreover, immunohistochemistry of ileal sections revealed the presence of IgG₁ and IgG₂ B lymphocytes in the villi and IgG₁ but not IgG₂ B lymphocytes in continuous Peyer's patch nodules. These data are consistent with the emergence of a type-1–like mucosal immune response in terminal ileal mucosa as calves recover from cryptosporidiosis.