Computer-aided modeling and analysis is an important step in the design of engineered systems. Unfortunately, developing such tools is hard and often prohibitively costly, and the analysis results are often of unknown dependability. We address two research problems whose solution could significantly improve the dependability and reduce the present high cost of modeling environments. The first problem is that, despite years of research, there are few successful models for component-based software development, and essentially no major successes for developing interactive systems—the last major success being the Unix pipe-and-filter model. It has been hypothesized that components based on APIenabled, architecturally compatible and composable mass-market application packages can succeed as a model for the component-based design of interactive systems. One of the main contributions of this work is an experimental systems test of this hypothesis in which we evaluate the feasibility of such an approach by using it to develop an industrially-viable environment for engineering modeling and analysis. The second problem we address is the need for techniques for specifying the semantics of high-level engineering modeling frameworks in terms of their corresponding mathematical meaning. Techniques for bridging this gap are crucial because they enable the rigorous specification of the semantics engineers require in order to have justifiable confidence in the high-level modeling frameworks. We hypothesize that formal techniques traditionally associated with the specification of semantics of software systems can be extended to the domain of engineering modeling and analysis, in general, and to reliability engineering, in particular. To test this hypothesis we will develop a formal specification of the semantics for a particular modeling framework in this manner, which will be the basis for assessing the feasibility of such an approach.