DEEPSOIL is a one-dimensional site response analysis program that can perform: a) 1-D nonlinear time domain analyses with and without pore water pressure generation, and b) 1-D equivalent linear frequency domain analyses including convolution and deconvolution. DEEPSOIL was developed under the direction of Prof. Youssef M.A. Hashash in collaboration with several graduate and undergraduate students including Duhee Park, Chi-Chin Tsai, Camilo Phillips, David R. Groholski, Daniel Turner, Michael Musgrove, Byungmin Kim and Joseph Harmon at the University of Illinois at Urbana-Champaign.