Selecting the correct garb for a 1950s dinner party doesn't require a freshly tailored vintage outfit. But you must forget what you know about "casual" attire -- at least for a few hours.
Today's casual dinner parties may allow khaki shorts, bowling shirts and flip-flops, but other guests would have been aghast if you'd darkened the doorway of a midcentury bash in such an ensemble.
To keep your dinner party looking the part, gents should wear a sleek suit and tie (either wide and pattered or skinny and plain would be retro-fashionable), while gals should wear a cocktail dress or skirt and blouse with kitten heels. And, if you're the hostess, be sure to slip on a vintage apron -- or a period reproduction -- as you perform your kitchenly duties.
Don't forget to dress your table, too. Busy patterns and bold colors were popular for both clothing and decoration, so don't be afraid to go big. If you don't happen to have a 1950s tablecloth handy, you could make your own using fabric from a thrift store or craft shop (look for large, watercoloresque floral or fruit prints on white backgrounds) and hem it with hemming tape if you don't have the time or patience to sew.