Increased woody plant cover in grasslands is a global phenomenon and a critical threat to conservation of grasslands and their biodiversity. Changes in land management, such as reduced fire frequency, can increase woody plant abundance, while other factors such as increased CO₂ concentration, N deposition, and habitat fragmentation might be contributing factors. We will present over 20 yrs of data from the Konza Prairie Biological Station (KPBS) and surrounding areas to elucidate the causes and consequences of the transition of C₄-dominated grasslands to shrublands and woodlands. The transition from grassland to shrubland is contingent upon fire-free intervals, which facilitate recruitment of new individuals and additional woody plant species. Once established, shrub cover can increase even with periodic fires, and infrequent fires can accelerate the spread of some shrub species contributing to a new dynamic state of shrub-grass co-existence in mesic grasslands. Results from an on-going experiment (the ‘Fire Reversal Experiment’) in which long-term fire treatments were ‘reversed’ on two watersheds previously burned annually in spring and two watersheds protected from fire for ~20 yrs to assess the legacy effects of fire history on trajectories of response to altered fire frequency will be presented. Although floristic richness or diversity changed little within 5 yrs, significant non-symmetrical changes in cover occurred among the major plant functional groups. Cover of woody vegetation and soil N availability decreased with repeated fires, and increased with fire exclusion. These results confirm rapid changes in soil properties and plant communities with initiation of frequent fire after long-term fire exclusion, with important implications for grassland management and restoration.