Open class may refer to:

• Open class (linguistics), a word class readily accepting new items
• Open (sport)
  • Open class (track and field), an event classification
  • Open 60 Class, a type of monohull sailboat
  • FAI Open Class, a glider competition class with unlimited wingspan
• Open class (computer programming), the ability to extend already-defined classes
• IBM Open Class (IOC), a C++ class library
• Open class system, a state of society