This paper describes the transaction support framework OPTIMA and its implementation for Ada 95. First, a transaction model that fits concurrent programming languages is presented. Then the design of the framework is given. Applications from many different domains can benefit from using transactions; it is therefore important to provide means to customize the framework depending on the application requirements. This flexibility is achieved by using design patterns. Class hierarchies with classes implementing standard transactional behavior are provided, but a programmer is free to extend the hierarchies by implementing application-specific functionalities. An interface for Ada programmers is presented and its use demonstrated via a simple example.