The present study was conducted to determine the impact of dietary energy and protein concentrations and lipid sources on growth performance and carcass traits of Pekin ducks. In Exp. 1, 15-day-old ducks (6 replicate pens, 60 ducks/pen) were randomly assigned to 4 dietary treatments with different metabolizable energy (ME) and crude protein (CP) concentrations (2,850 kcal/kg and 16%, 2,950 kcal/kg and 16.5%, 3,050 kcal/kg and 17.0%, and 3,150 kcal/kg and 17.5%) based on body weight (BW). In Exp. 2, 20-day-old ducks (4 replicate pens, 60 ducks/pen) were randomly allotted to 3 dietary fat sources (soybean oil, lard, and palm oil) with or without emulsifier in a 3 × 2 factorial arrangement. In Exp. 1, increasing ME and CP level improved (P < 0.05) body weight gain (BWG) and cost-to-gain ratio linearly, but reduced (P < 0.05) feed intake (FI) and feed-to-gain ratio (F/G) linearly. Breast skin thickness and liver redness (a*) value increased (P < 0.05) linearly with the increasing ME and CP level. In Exp. 2, no interactions between fat sources and emulsifier were observed. Feeding lard and palm oil diets increased (P < 0.05) final BW and BWG compared to soybean oil. Birds fed soybean oil and palm oil diets had lower (P < 0.05) FI compared to those fed lard diet. F/G in soybean oil and lard groups was higher (P < 0.05) compared to palm oil group. Birds in palm oil and lard groups had higher (P < 0.05) European production efficiency factor than those in soybean oil group. The addition of emulsifier increased (P < 0.05) BWG. In summary, the optimal ME and CP level for roasting was 2,950 kcal/kg ME and 16.5% CP and the palm oil was better than soybean oil and lard in Pekin ducks from 15 to 40 D of age. © 2019 Poultry Science Association Inc.