This research set out to clarify the construct of systems thinking and to define it as a conceptual framework apart from systems science, systems theory, systems methods, and other perceived synonyms. Greater clarity in the systems thinking construct will assist any one of the many current implementation efforts in which systems thinking is being applied in both scientific disciplines and practical fields. The ambiguities of the systems thinking construct are central to the challenges people face in understanding and implementing systems thinking. The research reveals four universal patterns of thinking that make up the core pillars of systems thinking.