The objective of this study was to evaluate the effect of mixing hay in calf starter on sorting behavior, DMI, and growth performance of dairy calves during the first 3 mo of life. Forty female Holstein calves were fed milk replacer containing 28% CP and 15% fat (maximum intake: 1,105 g/d) until 56 d of age. Calves were fed a texturized calf starter (23.4% CP, 32.2% starch, 20.9% NDF on a DM basis) mixed with chopped Klein grass hay (CP 10.0%, NDF 68.6% on a DM basis) at 90:10 ratio on an as-fed basis (MIX; n = 20) or fed the same starter and hay separately (CONT; n = 20) from d 14 to 90 of age. All feeds were offered ad libitum throughout the study. Particle distribution of the MIX ration was 1.2, 14.2, 82.3, and 2.3% on the upper sieve, the second sieve, the third sieve, and the bottom pan of Penn State Particle Separator, respectively. The CONT calves consumed starter and hay at 77:23 and 96:4 ratios on an as-fed basis before and after weaning, respectively, indicating that MIX calves were offered a solid feed diet containing less hay before weaning but more hay after weaning relative to what CONT calves consumed. Treatment did not affect total DMI (sum of milk replacer, calf starter and hay), ADG, and other growth variables before weaning (d 14 to 55). However, calves on MIX treatment decreased total DMI (3,273 vs. 3,495 g/d; P < 0.05), ADG (1.20 vs. 1.31 kg/d; P < 0.05), and heart girth gain (0.39 vs. 0.44 cm/d) compared with CONT calves after weaning (d 56 to 90). Although MIX calves sorted against particles on the upper sieve of Penn State Particle Separator (Sorting index = 85.5%; P < 0.01) after weaning, dietary NDF content consumed by post-weaned calves (% of total DMI) was greater for MIX than CONT calves (23.6 vs. 22.8% P < 0.05). These results suggest that inclusion of 10% hay in a calf starter may decrease DMI and growth performance after weaning even if calves sorted against hay to some extent.