A method of making apertured films including the step of perforating films of thermoplastic materials with embossing rolls engraved with patterns which form small slits or incipient slits in the sheet. The patterns are such that the design on the roll includes lands, or raised areas, which cross lands of the opposing roll at an acute angle. The perforated or partially perforated film formed may then be further processed by orientation, uniaxial or biaxial, simultaneous or sequential; by heat treatment; or both to modify the porosity, hole size, or other properties as desired.