Angus × Simmental cows ( = 48, BW = 594 kg, BCS = 5.26, age = 2.7) pregnant with male fetuses were used to determine the effect of selenium source during the last 80 d of gestation and first 108 d of lactation on progeny feedlot performance. At 203 d of gestation, cows were blocked by BW, breed composition, and calf sire and randomly allotted to 1 of 3 treatments: no supplemental Se, 3 mg/d inorganic Se (sodium selenite), and 3 mg/d organic Se (Sel-plex). Maternal diets were formulated to contain 10.4% CP and 0.90 Mcal/kg NE during gestation and 12.1% CP and 1.01 Mcal/kg NE during lactation. Basal diets contained 0.07 and 0.11 mg/kg Se for gestation and lactation diets, respectively. Diets were fed daily as a total mixed ration, and no additional Se, 3 mg/d Se as sodium selenite, or 3 mg/d Se as Sel-Plex were top-dressed daily. Treatment diets were fed through 108 d postpartum (DPP). At 108 DPP cow-calf pairs were commingled until weaning at 210 DPP. At 28 d postweaning, steers ( = 47, BW = 301 kg) were placed in individual pens and fed a diet formulated to provide 13.9% CP and 1.24 Mcal/kg NE. No supplemental Se was fed; however, basal Se concentration was 0.10 mg/kg. The diet was delivered as a total mixed ration once daily. Steers were slaughtered at a target BW of 625 kg. Steers from cows supplemented with organic Se tended to enter the feedlot heavier ( = 0.06) than steers from cows supplemented with inorganic Se. There was no difference in ADG among treatments ( ≥ 0.73), but steers from organic Se cows tended to spend fewer days on feed compared to steers from inorganic Se cows ( = 0.09). Steers from organic Se cows had a greater overall DMI compared to steers from inorganic Se cows ( = 0.04), but there was no difference in overall G:F ( = 0.49). Dressing percentage was greater for steers from cows fed no Se compared with steers from cows fed either inorganic or organic Se ( = 0.03). Maternal Se source had no effect on HCW, back fat, percentage KPH, LM area, yield grade, marbling score, or quality grade distribution ( ≥ 0.17) of progeny. In conclusion, maternal supplementation with organic Se appears to have a long-term benefit on intake of steer progeny and may result in improvements in growth that could decrease days on feed.