Abstract: A cap which is adjustable in size from a "small" size to an "extra large" size without destroying the aesthetics of the "Norwegian" or "Skilegion" design is provided by modifying the shape of the side panel. The side panel is shaped such that when laid-out flat the upper edge of the posterior portion extends along a shallow concave arc of curvature and the lower edge extends along a low convex arc of curvature. As a result of this configuration, the length of the upper and lower edges of the posterior portion is greater than length of the posterior portion of a conventional "small" size cap by an amount which is at least equal to the total size adjustment which the cap is required to accommodate. An elastic member is fastened at its opposite ends to spaced points on the posterior portion of the side panel, adjacent the lower edge thereof.