An object-oriented programming language is one that allows or encourages, to some degree, object-oriented programming methods.

Though Simula (1967), a language created for making simulation programs, was probably the first language to have the primary features of an object-oriented language, Smalltalk is arguably the canonical example, and the one with which much of the theory of object-oriented programming was developed.

These languages include "pure" object-oriented languages such as Smalltalk, Eiffel and Ruby, which were designed specifically to facilitate - even enforce - object-oriented methods; languages such as Java and Python, which are primarily designed for object-oriented programming but have some procedural elements; and languages such as C++, Fortran 2003, and Perl, which are historically procedural languages that have been extended with some object-oriented features. Oberon (and its successor Oberon-2) include most of the functionality of objects (classes, methods, inheritance, and reusability) but in a distinctly original, and elegant, form.

Some languages include abstract data type support, but not all of the features of object orientation (eg, Modula-2 which provided excellent encapsulation and information hiding). These are sometimes called object-based languages.

Inheritance and polymorphism are usually used to reduce code bloat , but abstraction and encapsulation are used to increase code clarity, quite independent of the other two.

Languages with object-oriented features

• Ada 95
• boo
• C++
• C#
• ColdFusion
• Common Lisp
• CorbaScript
• COOL (Object Oriented COBOL)
• D
• Delphi
• ECMAScript (JavaScript)
• Eiffel
• Fortran 2003
• Gambas
• IDLscript
• incr Tcl
• J
• Java
• JavaScript
• Lexico
• Lingo
• Modula-2
• NewtonScript
• Oberon and Oberon-2
• Objective-C
• Perl 5
• PHP
• PowerBuilder
• Python
• REALbasic
• Ruby
• Sather
• Scala
• Self
• Simula
• Smalltalk
• STOOOP
• Superx++
• VBScript
• Visual Basic / VB.NET
• Visual Prolog
• XOTcl
• ZZT-oop