Scratch an art dealer, and you’ll often find a curator. That’s the case with Craig Starr, who seems to operate in the secondary art market mainly to support his persistent curatorial itch. For nearly a decade, he has been mounting sharp-focus shows of historical works by prominent American postwar artists in his jewel-box gallery on the Upper East Side.

Mr. Starr’s latest effort — one of his best — is “Robert Rauschenberg: The Fulton Street Studio, 1953-54.” With 15 works borrowed from private collections, this exhibition delves into a formative period in the development of Rauschenberg (1925-2008), when he was in his late 20s and moving fast. It presents his sensibility in a nutshell, his broad aesthetic range, omnivorous curiosity, playfulness and intuitive elegance.