Muzaffarnagari, known for its heaviest body weight among Indian sheep breeds, is distributed in and around Muzaffarnagar district of western Uttar Pradesh and also in some parts of Rajasthan, Haryana and Delhi states. In this breed, the wool production is low and wool quality is very course, not suitable for carpet manufacture, hence it is mainly reared for mutton production. For evaluating growth traits i.e. body weights at birth, 3, 6, 9 and 12 month age and wool production traits viz. greasy fleece yields of lambs in first & second six monthly clips, the data on 1028 Muzaffarnagari lambs born under Network Project on Sheep Improvement during years 2010-14 at Central Institute for Research on Goats, Makhdoom, Farah, Mathura (UP) were recorded for various growth and wool traits. In addition to production traits, the data on some reproduction traits viz. tupping, lambing on available basis, lambing on bred basis and twinning of ewes were also recorded. The overall least squares means for body weights at birth, 3, 6, 9 and 12 months age were 3.52±0.02, 15.51±0.13, 23.62±0.19, 28.05±0.19 and 32.92±0.21 kg, respectively and for lambs 1st and 2nd six monthly clips 525.08±5.65 and 555.81±6.94g, respectively. The effect of sex, year of lambing, parity and type of birth of lambs had highly significant (P<0.01) influence on all growth and wool production traits except non significant effect of type of birth on second six monthly clips. On comparison, male lambs were found superior than female lambs for all body weights and fleece yields. During year 2013, all the body weights and greasy fleece yields were recorded to be highest. Parity of ewes did not show any definite trend for growth traits while type of birth indicated that lambs born as single gained heavier weights at all growth stages and produced heavier clips than multiple born lambs. Tupping, lambing on available basis, lambing on bred basis and twinning ranges respectively 86.9-100.0, 74.3-91.0, 83.2-92.5 and 10.9-20.3%. This study indicated that selection of breeding rams based on their six month body weight was effective for genetic improvement of Muzaffarnagari sheep for body weights and wool production and pre-weaning (0-3 month) growth period of lambs was found very crucial which warrants proper management, feeding and health care for overall productivity and better profitability of Muzaffarnagari sheep.