The ASW 15 has shoulder-mounted wings and an all-flying tailplane, with its single tow-release placement a compromise between winching and aerotowing.

The later ASW 15B had several improvements, including a tow-release placed on the plane of symmetry, an 11 cm taller rudder, a slightly larger main wheel, and the provision of a 90-litre water ballast system.

Rot due to fungus infestation was found in an early example, leading to an Airworthiness Directive.

Starting with serial number 356, balsa wood was abandoned in the construction in favour of synthetic foam.

In 1971 and 1972, the American pilot Karl Striedieck set world out-and-return distance soaring records three times flying an ASW 15, including one flight of 1,009.854 kilometres (627.494 mi) on October 15, 1972.