Victor Costa Peplum Dress
Nylon, back zip closure. Circa 1970's in a size 6.
A great 1987 NYTimes article on the designer can be found here:
Shown styled with the Zana Bayne choker belt, available here:
Model is 5'11", 32" bust/28" waist/41" hips. Wears a modern women's size 6-8.