[en] Fairly complete systematics of linear momentum transfer distributions now exist for a variety of ions up to A = 20 and bombarding energies of E/A approx.> 10 MeV. On a per nucleon basis the proton is the most effective agent of linear momentum transfer and heavy ions the least effective. For heavy ions (6 less than or equal to A less than or equal to 20) the average linear momentum transfer scales directly with projectile mass, producing a universal curve in terms of < p₁₁>/A. For all projectiles the average linear momentum transfer reaches a maximum at intermediate energies and then falls off gradually. For protons this maximum value is about 300 - 350 MeV/c, in contrast with the universal heavy ion value of < p₁₁>/sup max/ approx. = 145 A MeV/c. Many of the qualitative features of the light-ion data can be understood in terms of fundamental N-N, d-N and α-N scattering processes. Intranuclear cascade calculations are consistent with the data although inadequacies in the mode are apparent. Finally, the need for an intensified theoretical effort to explain these data is clearly essential if these basic features of nucleus-nucleus collisions in the intermediate-energy regime are to be understood