The Welsh Terrier is a square-proportioned, compact, sturdy dog of medium size, capable of running at good speed for long distances and then bolting or dispatching its quarry. Its gait is free and effortless, with good reach and drive. Its coat is double, with a short, soft undercoat and a hard, dense, wiry outer coat. The expression and demeanor are confident and alert.

The Welsh, although more mild-mannered than many terriers, is still playful and mischievous enough to provide plenty of entertainment and challenges, yet it is calm enough to be a reliable house pet. It is independent, inquisitive and sensitive, reserved with strangers and possibly scrappy with other dogs and pets. It needs daily exercise in a safe area. It tends to dig and bark.