Can you wear a cotton sport coat with wool pants? Yes. Should you? No.
The fabrics simply don't go together, so don't force something that isn't meant to be. Cotton sport coats are wonderful, and wool pants are great, too. They just shouldn't be worn together.
Cotton Sport Coats
Cotton sport coats are meant to be worn in warm weather. Both in function and style, they are ideal to dress up a casual occasion and can be worn with a dress shirt and tie. Cotton comes in many great fabrics: twill, seersucker, canvas, denim, poplin and corduroy, among the most popular. Polo Ralph Lauren, Brooks Brothers, JoS. A. Bank, Nautica, The Men's Wearhouse and Macy's have a great selection of style and color in cotton sport coats this spring.
The gold-standard fabric for mens dress pants is 100% wool. Wool comes in many weights and styles including gabardine, plain-weave and crepe. Wool pants come in heavier weights, like flannel for cold weather and tropical weight for warmer months. Great wool pants can be found at JCP, Polo Ralph Lauren, Hickey Freeman, JoS. A. Bank, and The Men's Wearhouse.
What Pants to Wear With Cotton Sport Coat
Cotton sport coats pair great with 100% cotton pants in khaki twill, poplin, and seersucker. They also pair well with linen pants and, of course, jeans. As denim has become the go-to fabric in men's pants, the cotton jacket in spring and the wool jacket in fall makes a great pairing with jeans.
What Coat to Wear With Wool Pants
Wool pants are designed as a stand-alone pant. That means they should not be worn as part of a suit. Wool can be paired with a sweater, knit shirt or woven shirt. They can be worn with a dress shirt and tie, as well. Wool pants can, indeed, be worn with the right sport coat. However, under no circumstance should you attempt to "match" a standalone sport coat and a pair of wool pants. The color and fabric will simply never match. In most cases, a subtly patterned or solid black or navy sport coat in pure wool looks best with wool pants.