Molecular clouds and their stellar populations exhibit a number of apparently disconnected properties, such as 1) apparent virialization at all scales from GMCs to dense cores; b) Highly filamentary structure of the intermediate-to-high-density regions, often with high-mass star-forming "hubs" at their junctions; c) stellar-age histograms that peak at a certain age and decline at both larger and smaller ages; d) a large scatter in their instantaneous star formation efficiencies; e) mass and age radial gradients in their stellar associations. All of these properties can be understood in terms of a scenario in which the clouds are undergoing global and hierarchical collapse, consisting of hierarchically-nested collapsing structures, so that small-scale (SS) collapses occur within, and simultaneously fall into, larger-scale (LS) ones. Ths implies that all scales appear near equipartition between the kinetic and gravitational energies, resembling virialization. The largest scales collapse in nearly pressureless form, causing them to contract first along their shortest dimensions, forming sheets and filaments. The collapse implies that the star formation rate (SFR) increases in each star-forming region until massive stars begin to form and erode the parent cloud, causing the SFR to decrease again, producing the observed stellar age histograms. Finally, the hierarchical structure of the gas is imprinted in the stellar population, causing the observed age and mass segregation.