They were fabric covered, the wings having a wooden structure and the control surfaces and fuselage constructed from metal frames.

The standard cabin can be subdivided again into three groups, early examples having a boat-tail skylight (QDC, OEC & UEC), mid series aircraft with a faired skylight (CJC, UIC, UKC, YKC) or late examples with no skylight (DJC-S, HKS, ZKS, UKC-S UKS-7, VKS-7, YKC-S, YKS-6 & 7, ZKS-6 & 7).

From about 1937, all S series aircraft had wings lacking leading and trailing edge cutouts.

Like most Waco aircraft, the S series were available with many different engines (identified by the first letter of the type designation).

The S series proved to be popular with both commercial and private pilots and over 50 were still airworthy in 2001, including examples of the CPTP VKS-7F version.