The theories related to the strength-thickness relationship of solid-asphalt-solid systems are discussed and their limitations in explaining the “strength-thickness” rule are presented. It is postulated that the restraining action of the boundary conditions is responsible for the observed strength-thickness rule. With respect to the failure mechanism of the solid-asphalt-solid systems, it is indicated that the three types of failure, brittle fracture, tensile rupture, and shear failure, observed in thin films of asphalt are related to the restraining action of the boundary conditions. It is also indicated that, according to thermodynamic principles and concept postulated by Bikerman, the failure in the “properly formed” solid-asphalt-solid systems can be considered as cohesional rather than adhesional. Using the time-temperature superposition principle, the temperature-dependence function of solid-asphalt-solid systems is also determined. It is shown that in confirmation with previous investigations in solid-asphalt-solid systems the temperature-dependence function of asphalt is considerably reduced. A master curve has also been prepared for the tensile-strength-film-thickness relationship of asphalt.