Formal methods using text to specify abstract data types (ADTs) are powerful, but they require great effort and a high level of expertise. Visual programming languages present an alternative way of programming but are limited to building small programs. This research presents an approach for specifying ADTs using a combination of text and visual objects. Furthermore, it presents two algorithms to map those specifications into imperative code. DataLab, a computer program for the MacintoshTM computer, is an implementation model for this approach. DataLab consists of two major components: a graphical editor and a source code generator. The graphical editor allows the user to build a specification consisting of an interface part and an implementation part for each ADT. The interface of the ADT is specified textually in a window that is part of the graphical editor. The implementation part of the ADT includes the operations, which are specified in Data Lab as a set of "Condition/Action" transformations. These transformations describe the behavior of the operations and are built by selecting graphical objects from a palette and placing them on the screen. The source code generator takes the specification of the ADT as an input and generates an encapsulated Pascal code. It consists of two algorithms: the first maps the specification into its semantics, and the second maps the semantics into Pascal modules. / Graduation date: 1990