Abstract: The recently discovered iron pnictide compounds (critical temperature Tc = 55 K) ended the monopoly of cuprates in the family of high-Tc superconductors. As with cuprates, the pairing mechanism is important for understanding the new system. In this article, we employ high-resolution angle-resolved photoelectron spectroscopy to characterize the band structure and Fermi surface topology of iron pnictides, as well as their evolution with dopant concentration. We observe isotropic but Fermi-surface-dependent superconducting gaps in this system, and propose that inter-Fermi-surface interactions play an important role in the pairing mechanism.