Field research was conducted for 2 years to determine the effects of N and S sources and rates on stockpiled tall fescue (Festuca arundinacea Schreb.) forage yield, quality, and mineral concentrations at different autumn harvest dates and a forage harvest the following spring. High lysine fertilizer (HLF), which contains approximately 6% total N and SO 4 , produced dry matter (DM) yields similar to NH 4 NO 3 when combining the autumn stockpiled yield with a harvest the following spring. However, NH 4 NO 3 produced more stockpiled forage than HLF in 1 of 2 years. Combining autumn and spring harvests, each pound of fertilizer N increased forage yield by 24.8 to 27.5 lb DM during the 2-year study period. Adding N increased forage quality, regardless of the N source. But adding S did not improve forage quality or DM yield. Tall fescue harvested in late October or early November compared to early October had greater DM yield in 1 of 2 years (9%) and lower crude protein and in vitro dry matter digestibility (IVDMD) both years. Growers deciding between N sources should base their decisions on forage supply and cost because cumulative performance of tall fescue using both N sources was similar.