Integrating concurrent and object-oriented programming has been an active r
esearch topic since the late 1980's. There is now it plethora of methods fo
r achieving this integration. The majority of approaches have taken a seque
ntial object-oriented language and made it concurrent. A few approaches hav
e taken a concurrent language and merle it object-oriented. The most import
ant of this latter class is the Ada 95 language, which is an extension to t
he object-based concurrent programming language Ada 83. Arguably, Ads, 95 d
oes not fully integrate its models of concurrency and object-oriented progr
amming. For example, neither tasks nor protected objects are extensible. Th
is article discusses ways in which protected objects can be made more exten
sible.