The paper explores the formation of galactic disks within hierarchical clustering models of structure formation. It assumes that disks form with a fixed fraction of the mass and angular momentum of their surrounding dark haloes. The models predict that disk properties, such as size and rotation velocity, are closely related to the mass and angular momentum of the halo. These predictions match observed data on present-day disks and damped Lyα absorbers in quasar spectra. The models show good agreement with the observed scatter in the size-rotation velocity plane and the slope and scatter of the Tully-Fisher relation. The zero-point of the Tully-Fisher relation is consistent with observational values derived from disk dynamics. High-redshift disks are predicted to be small and dense, and could merge to form elliptical galaxies. The paper also discusses the implications of these models for the distribution of damped Lyα absorbers and the evolution of disk populations in different cosmological models. The results suggest that disks with rotation velocities exceeding 200 km/s can account for a significant fraction of observed damped Lyα systems at z ~ 2.5. The paper concludes that the models provide a consistent framework for understanding the formation and evolution of galactic disks within hierarchical cosmogonies.The paper explores the formation of galactic disks within hierarchical clustering models of structure formation. It assumes that disks form with a fixed fraction of the mass and angular momentum of their surrounding dark haloes. The models predict that disk properties, such as size and rotation velocity, are closely related to the mass and angular momentum of the halo. These predictions match observed data on present-day disks and damped Lyα absorbers in quasar spectra. The models show good agreement with the observed scatter in the size-rotation velocity plane and the slope and scatter of the Tully-Fisher relation. The zero-point of the Tully-Fisher relation is consistent with observational values derived from disk dynamics. High-redshift disks are predicted to be small and dense, and could merge to form elliptical galaxies. The paper also discusses the implications of these models for the distribution of damped Lyα absorbers and the evolution of disk populations in different cosmological models. The results suggest that disks with rotation velocities exceeding 200 km/s can account for a significant fraction of observed damped Lyα systems at z ~ 2.5. The paper concludes that the models provide a consistent framework for understanding the formation and evolution of galactic disks within hierarchical cosmogonies.