Abstract: A lamp fixture for mounting a high intensity discharge (HID) lamp. The lamp fixture integrates components needed to operate the HID lamp, including a lamp socket and a ballast, into a compact assembly covered by an enclosure. The fixture facilitates dissipation of heat from the lamp and ballast through a base mounting so that thermal insulation of the ballast transformed is not required, thereby reducing the weight of the device. The fixture may further include a diffuser mounted to the enclosure to distribute light from the HID lamp in a uniform manner. The fixture is particularly useful for mounting HID lamps within illuminated signs.