Conventional wisdom says dark trousers and a light shirt. Hollywood says wear all black.
Turn both on their heads. For a summer evening, try white trousers (hey! it’s summer, you can’t wear these after Labour Day) and a dark shirt.
White, lightweight wool pleated trousers (lined to the knee in muslin — or they’d be see-through), tan calf belt, dark blue shirt with white windowpane overlay by Brooks Brothers (ca. 2000?) Spectator or light brown loafers (although I usually wear black shoes in the evening) continue the evening’s palette. I have seen this work very well with navy Belgian slippers. Finding a blue leather belt can be difficult, however.
Have a swellegant weekend. If you are in the metro D.C. area, don’t forget about the Doc Scantlin Dancin’ under the stars concert at Reston Town Center. Wear your white dinner jacket.