In 2010, WQS C4 S2 testcrosses were evaluated at two locations, Madison and Arlington. There were two replications at each location. The 200 entries consisted of 188 S2 families crossed to LH244 and twelve hybrid checks. The WQS C4 S2 trial represents the fifth cycle of selection in the WQS breeding population. The 20 best families will be recombined to create WQS C5. The planting date at Madison was 05/06/2010. The Arlington trial was planted on 05/20/2010. The average planting density was 32300 plants/acre at both locations. Temperatures throughout the spring and summer were above average for our area. A rapid accumulation of growing degree days was noted throughout the season. No major lodging problems were observed this year. Due to mechanical malfunctions, significant delays occurred during harvesting primarily for the Arlington location. Advancement decisions were done using primarily the West Madison yield and dry matter data. Based on forage yield, 36 WQS C4 S2 testcrosses were chosen for nutritional evaluation (WQS C4 S2 – Forage yield evaluation). Nutritional evaluations included assessment of neutral detergent fiber (NDF), in vitro true digestibility (IVD), in vitro NDF digestibility (IVNDFD), crude protein (CP), and starch concentration. Based on these values, milk/ton of forage and milk/acre were estimated based on MILK2006, which uses forage composition (NDF, IVD, IVNDFD, CP, and starch) to estimate potential milk production per ton of forage. Forage yield is then used to estimate potential milk per acre (WQS C4 S2 – Forage quality evaluation).