The Advanced Fiber Information System (AFIS) was used to evaluate cotton grown under various conditions. AFIS quality characteristics measured included fiber properties' distributions such as length, diameter, maturity, fineness, and neps. The AFIS system individualizes and cleans the fibers before presentation to an electro-optical sensor. High velocity airflow moves individualized fibers past the optical sensor. The fibers or neps present in the sample generate electrical signals characteristic of fibers or neps. The interruption of the light beam impinging on the electro-optical sensor produces two types of signals of interest. One signal results from the light beam being blocked (attenuated) by the fiber (or nep in the case where the nep module is in use) in proportion to its mean optical diameter and in direct relation to its time of flight in the sampling volume. The other is the result of the light scattered by the same fiber at 40 degrees from the beam direction. The computer software analyzes the electrical impulses of both signals and presents the data according to parameters specified for the particular test. Data from the attenuated signal is used to directly measure individual fiber length and diameter (L&D) and NEPS. Data from the 40 degree scattering signal yields fineness and maturity (F&M) fiber data. Sample preparation consists of drawing slivers of suitable lengths as required by the particular AFIS program in use. The weight of fiber per replication for NEP measurement is set between 400 and 600 mg. The number of fibers per replication for F&M and L&D measurements may be set as high as 10,000. Individual replications can be measured on samples ranging in size from a few milligrams to several hundred milligrams.