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The importance of angular momentum in regulating the sizes of galactic disksand by this their star formation history is highlighted. Tidal torques andaccretion of satellites in principle provide enough angular momentum to formdisks with sizes that are in agreement with observations. However three majorproblems have been identified that challenge cold dark matter theory and affectmodels of galaxy evolution: (1) too much angular momentum is transferred fromthe gas to the dark halos during infall, leading to disks with scale lengthsthat are too small, (2) bulgeless disks require more specific angular momentumthan is generated cosmologically even if gas would not lose angular momentumduring infall, (3) gravitational torques and hierarchical merging produce aspecific angular momentum distribution that does not match the distributionrequired to form exponential disks naturally; some gas has exceptionally highangular momentum, leading to extended outer disks while another large gasfraction will contain very little specific angular momentum and is expected tofall into the galactic center, forming a massive and dominant bulge component.Any self-consistent theory of galaxy formation will require to providesolutions to these questions. Selective mass loss of low-angular-momentum gasin an early phase of galaxy evolution currently seems to be the most promisingscenario. Such a process would have a strong affect on the early protogalacticevolution phase, the origin and evolution of galactic morphologies and linkcentral properties of galaxies like the origin of central massive black holeswith their global structure.Comment: 16 pages, 7 postscript files, requires kapproc.cls and procps.sty; to  appear in "Penetrating Bars Through Masks of Cosmic Dust: The Hubble Tuning  Fork Strikes a New Note", ed. Block, Freeman, Puerari and Groess, Dordrecht:  Kluwe

Galaxy Formation and the Cosmological Angular Momentum Problem