In recent years, systems engineering and Project Management Bodies of Knowledge have been rapidly growing. However, despite the vast amount of literature available on systems engineering and project management, about two-thirds of all projects still fail. A review of both project management and systems engineering publications reveals that most of these works focus on processes. We suggest focusing on people—project managers and systems engineers. One of our previous studies dealt with project managers; this article focuses on systems engineers. This article presents findings of a study aimed at exploring the relationship among systems engineers' capacity for engineering systems thinking (CEST), project types, and project success. The instrument used in this study was a self-report questionnaire, composed of three parts. The first part assessed the participants' CEST, the second part assessed several measures of project success, and the third part assessed four dimensions of project type. The simple random sampling method was used, and the sample included 114 senior systems engineers who were randomly selected from the sampling frame. The study findings show that there is a statistically significant correlation between CEST and project success. The extent of the project's novelty, complexity, and technological uncertainty are moderator variables that affect this correlation.