The Perl 5 module Object::InsideOut provides comprehensive support for implementing classes using the inside-out object model. It implements inside-out objects as anonymous scalar references that are blessed into a class with the scalar containing the ID for the object (usually a sequence number). Object data (i.e., fields) are stored within the class's package in either arrays indexed by the object's ID, or hashes keyed to the object's ID. The virtues of the inside-out object model over the 'blessed hash' object model have been extolled in detail elsewhere. Briefly, inside-out objects offer the following advantages over 'blessed hash' objects: * Encapsulation * Field Name Collision Avoidance * Compile-time Name Checking