The problems associated with engineering tasks are often too large and complex for application of conventional software methods, but are suitable to application of expert system methods. Development of custom expert system applications is expensive and difficult, but expert system development tools provide the basic components needed to construct an expert system. Such tools enable engineers to implement expert system applications by entering knowledge specific to the particular problem they are attempting to solve. Because the choice of a development tool can determine the success of the resulting expert system application, the characteristics of these tools and of the target problem must be clearly understood before a selection is made. An overview of expert systems and development tools is given, characteristics of some common engineering problems are discussed, and selection criteria for tools well suited to these problems are presented. Implementation of a rule-based advisor to assist with tool selection is discussed briefly.