Nondestructive VIS/NIR reflectance spectroscopy measures cotton fiber strength (tenacity) by a two-step process. The first step is prerequisite to the second and is the result of an intrinsic characteristic of cotton. That is, a significant relationship exist between strength and certain other fiber properties. An equivalent argument is that strength cannot be independent of all fiber properties. In the second step, reflectance spectroscopy measures the other fiber properties. The two-step process permits the measurement of fiber strength and we refer to the general analytical process as a combination (Type C) sensing mechanism. The experimental evidence supports each step in the mechanism.