Most stores carry a wide range of cotton fabrics and cotton/polyester blends, but the quality varies considerably. Here are some tips for judging a fabric's quality before you buy:

Count the number of yarns per inch in both directions of the weave. Better fabrics have more yarns per square inch.

Hold the fabric up to the light. The tighter the weave, the less light will shine through. Look for uniform spacing between yarns. Beware of fabrics that appear to be thinner in some areas than others.

Inspect the twist of an individual yarn, preferably a yarn pulled from the lengthwise direction of the weave. A tightly twisted yarn is stronger and the fabric will be more durable. The presence of short, wispy fibers may be a sign of low quality yarns.

Inspect the yarns for variations in thickness. They should be uniform in size and thickness, although they may not be the same size in both directions, depending on the weave. (Keep in mind that slubbed yarns and irregular weaves are part of the appeal of some fabrics, especially handwovens.)

Scratch a small section of the fabric with your thumbnail to see if the yarns are distorted easily. Such fabrics tend to pull apart at the seams of close-fitting garments.

Check the fabric to see if the lengthwise and crosswise yarns intersect at right angles. Beware of fabrics with bowed or skewed grain.

Inspect printed fabrics to make sure the print is straight, especially in the case of stripes, plaids, checks and other designs with straight lines. The lines of the print should match the grain or torn edge of the fabric.

Inspect printed fabrics to make sure the colors are registered, with no overlapping colors, blurred prints or white outlines around the motifs.

Rub the fabric between your hands. A heavily sized fabric will feel chalky. It may appear to be coated with a filmy or powdery substance. Such fabrics usually are inferior.

Check the fabric for loose yarns to see if it unravels easily.

On twill fabrics, examine the angle of the diagonal twill line. A steep line is a sign of a tight, compact weave and a better quality fabric.

Scrunch a small piece of fabric in your hand and release it. If the fabric remains wrinkled, it probably will wrinkle easily.

Loosely gather up to a yard of the fabric in your hand to determine how it will work with a gathered or shirred style. Unroll a yard or more of the fabric and let it hang freely to determine how it drapes and falls.

Examine the fabric for one-way designs, luster, nap or other factors that may require special handling.

Sniff the fabric for unpleasant odors that may not wash out.

Compare the price with that of similar fabrics. Although price is one sign of quality or lack thereof, it is no substitute for a thorough look at the fabric. Some fabrics are true bargains and some are not.