In this era of extrasolar planet discovery and characterization, the leading theory for the formation of Jupiter-like planets is core accretion, in which a rocky core about 10 times the mass of Earth gradually gathers an extended gaseous envelope, which eventually collapses onto the core. One critical issue is the role played by angular momentum during the gathering phase, which limits the mass supply, alters the collapse structure, and generates a disk around the growing planet. This project will comprehensively model these effects, acting as an analytical guide to more complex modeling. It will also support an existing lecture series, Saturday Morning Physics, at the University of Michigan. The gathering phase, due to its long timescale, can be limited by the lifetime of the disk, so the protoplanet may fail to become a giant planet after all. This project models the interior structure of a growing, rotating protoplanet. Based on a heritage of rotating stellar models, a solution of hydrostatic equilibria will be found. How the equilibrium condition disappears depends on these rotational effects, leading to collapse, when runaway growth delivers most of the planet’s mass. The project additionally models how the disk generates and processes radiation, providing an important observational signature of forming giant planets. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and