We report results from high-resolution particle-mesh (PM) N-body simulations of structure formation in an Ω=1 cosmological model with a mixture of cold plus hot dark matter (C+HDM) having Ω cold =0.6, Ω ν =0.3, and Ω baryon =0.1. We present analytic fits to the C+HDM power spectra for both cold and hot (neutrino) components, which provide initial conditions for our nonlinear simulations. In order to sample the neutrino velocities adequately, these simulations included 6 times as many neutrino particles as cold particles. Our simulations boxes were 14, 50, and 200 Mpc cubes (with H 0 =50 km s −1 Mpc −1 ); we also did comparison simulations for cold dark matter (CDM) in a 50 Mpc box