The equilibrium structure and dynamics of a two-stranded coiled-coil polypeptide are investigated via Langevin dynamics simulations. An off-lattice model of the polypeptide chain is employed, which gives rise to a well-defined helical dimer native state and two-state folding kinetics. The behavior of the freely diffusing and surface-immobilized polypeptide is studied under different surface and denaturation conditions. The effect of surface immobilization on the distributions of structural and dynamical properties is considered in detail. The relationship between the simulation results and recent single-molecule fluorescence resonance energy transfer experiments performed on the two-stranded coiled-coil from the yeast transcription factor GCN4 (Jia et al. Chem. Phys. 1999, 247, 69; Talaga et al. Proc. Natl. Acad. Sci. U.S.A. 2000, 97, 13021) is discussed.