The crest bearing three cows’ heads, visible on the wall behind the sitter, indicates that this young man is a member of the prosperous Coymans family of Haarlem. The cows’ heads refer directly to the Dutch family name, which translates as "cow man." Archival and genealogical information, combined with the Latin inscription "AETA SVAE.22 / 1645" below the shield, identifies the sitter as Willem Coymans, who was twenty-two years old in 1645. The few paintings dated by Frans Hals tend to also provide the subjects’ ages, thus serving as genealogies. In addition to this likeness of Willem, Hals painted the portraits of at least four other members of the Coymans family.
Hals was the preeminent portrait painter in Haarlem, the most important artistic center of Holland in the early part of the seventeenth century. He was famous for his uncanny ability to portray his subjects with relatively few bold brushstrokes, and often used informal poses to enliven his portraits. Here, Willem Coymans is informally seated in a chair, with one arm hooked casually over its back to enhance the lifelike quality of his portrait. Coymans, resplendent in his elegant clothes, sports a brocaded jacket with slit sleeves over a pleated white shirt. The dazzling brushwork so typical of Hals is especially evident in the gold embroidery and the crispness of the sleeve. The pom-pom on his hat, pushed forward at a rakish angle, and the oversized collar of his shirt mark Willem as a dandy.