Increasing concerns about energy security and climate change mitigation have led to significant policy support for biofuels, particularly for cellulosic biofuels. This paper examines the short- and long-run effects of Renewable Fuel Standard (RFS) on the mix of biofuel feedstocks, food, fuel and wood markets and land use change by using an economic model that integrates the agriculture, forest and transportation fuel sectors. Our results show that RFS would lead to the production of about 1600 billion liters of corn ethanol over the 2010-2035 periods, which could constitute a maximum of two-thirds of the cumulative biofuel production; the remaining mandate is met by advanced biofuels. The logging and milling residues are the primary initial providers of biomass feedstocks. After year 2025, energy crops and crop residues will play the leading role in cellulosic feedstocks production. Producing these biofuels will not cause significant land use change between and within agricultural and forest sector as compared to the business-as-usual (BAU) case. While the RFS could significantly affect production, exports and prices of crop and livestock commodities relative to the BAU case, its impacts on the forest sector is found to be relatively small except for pulpwood related products in the long term. Overall, the RFS reduces cumulative social welfare over 2010-2035 periods by $78.8 Billion relative to the BAU case.