I live in the Chicago area in a 2-story cape cod. When I went into my attic to replace a lightbulb (on the wall, not on the ceiling) I saw that water had been dripping out of the lightbulb socket. What would cause this and how do I fix it? Who do I call? I called a roofer and he said the roof is not leaking. Thanks for any help!

Look for a way water can get their. 2 thoughts: 1 from a conduit that goes up to maybe an outside light or receptacle. Another could be a leak not directly above and following a wire or wood angled down.

The water could be the result of condensation build up. A lot depends how well, or not, the attic is insulated, heated, proper ventilation, etc. I live in the Chicago area and had the some problem with the bedroom lights in a bi-level house. The conduit in the crawl space was getting cold and sweating, and when I pulled the wires they had rust marks on them. Installed a roof fan w/humidistat and no problems since. Even though yours is a wall lamp, this could be a possible cause. However, as start stated, water can travel and there may be leak somewhere, not necessarily the roof.

Is their Air conditioning ductwork above.
I have seen lightbulbs full of water? Strangest thing.