The modern wealth of data on extrasolar planets is a boon to theoretical studies of the origin and evolution of planetary systems. However the great diversity of exoplanet systems also poses challenges to the goal of a coherent, unified theory of planet formation. This talk will present dynamical models of the most crucial stages of planet growth. First I will address the origin of the solid building blocks known as planetesimals. Aerodynamic processes, highlighted by the streaming instability, play a crucial role in the emergence of planetesimals within turbulent gas disks. Such models of early planet growth can be tested with exoplanet statistics and, more directly, with studies of the Kuiper Belt. Shifting to later phases, I will address the accretion of giant planet atmospheres onto protoplanetary cores. I will present models that challenge the conventional wisdom that a 10 Earth mass core is needed to trigger runaway gas accretion. In particular lower core masses suffice in the outer regions of the protoplanetary disk. These models are crucial for understanding the HR 8799 multiplanet system and others that will be discovered in current and future imaging surveys. I will conclude by discussing future prospects for theoretical models to improve our understanding of planets near and far.