Around town under normal conditions, hardly ever. When rambling around in the outdoors, almost always something - in cold weather, a balaclava; in hot or sunny weather, a full brimmed hat basically like your military boonie. Most of outdoors experience has been in the desert SW, and a hat that shades all of the old bean is really, really important. I have always been partial to a cotton hat that could be soaked in water, with a dark underlid to help with glare. It is also important to have a chin cord so the thing will stay on inthe wind. A lot of environments (caves, especially) require a protective hard hat. My favorite is a Petzl climbing helmet. When on the job (before retirement) I theoretically wore the NPS ranger flat hat, which is the most gorgeously impractical headgear ever invented.<br><br>Ball caps are pretty useless, except for fashion statements.