Our objective was to determine the effects of pair vs individual housing on acquired immunity and body weight (BW) of pre-weaned Holstein calves. Calves with successful passive transfer of immunity (STP >5.5 g/dL) were enrolled into pair (n = 28) or individual (n = 14) housing on 5 ± 1 d postpartum. Regardless of treatment, 2.1 m² of housing space/calf was available. In the paired treatment, only 1 calf was used for data collection. Milk replacer (protein 26: fat 20; 3L) was fed 2x/d, and grain and water was provided ad libitum. On 7 ± 3 d postpartum, calves were injected with 1 mL of keyhole limpet hemocyanin (KLH; 0.1 mg), Quil-A adjuvant (0.5 mg), and nonpyrogenic saline. A secondary injection was given on d 21 ± 3 including KLH (0.1 mg), Quil-A (0.5 mg), and heat-killed Candida albicans (CA, 2 × 10⁶ cells) in nonpyrogenic saline. Serum samples were collected 0, 7, and 14 d after injections. IgG from each collection day were evaluated by ELISA. On d 28 ± 3, calves were inoculated with intradermal injections of CA (2 × 10⁶ cells) or saline in the neck to evaluate cell-mediated immunity. Injection sites were measured with calipers at 0, 6, 24, and 48 h post-injections. A stimulation index (SI) was calculated by mean CA response over saline response in cm. BW was measured weekly, at weaning, and 1 wk-post-weaning. Separate linear MIXED models (SAS 9.4, Cary, NC) were used to evaluate the effects of housing treatments on CA, IgG, and BW. The SI was similar in both housing treatments (P = 0.81). However, SI increased over time (P < 0.01), and peaked at 24 and 48 h compared with 0 and 6 h (P < 0.01; h 0 = 1.10, h 6 = 1.18, h2 4 = 1.58, h 48 = 1.58 ± 0.08 cm). IgG concentrations to KLH were similar between both housing treatments (P = 0.78). IgG concentrations at d 7 were lower than d 0 and 14, regardless of treatment (P < 0.01; d0 = 0.77, d7 = 0.56, d14 = 0.71 ± 0.06 ELISA units/d). Maternal antibodies may have interfered with binding of KLH. ADG (P = 0.35) and BW gain 1 wk post-weaning were similar between treatments (P = 0.67). Regardless of housing type, calves with successful maternal antibody transfer had similar adaptive immune responses and BW gains.