The book’s final chapter discusses the overlap between Collins’s previous book, Built to Last, and Good to Great. In the initial stages of the research that went into Good to Great, Collins and his team agreed that they would act as if Built to Last had never even existed in order to avoid confirmation bias. However, as Collins now compares the two works, he summarizes his findings into the following four ideas: (1) In the perennially great companies in Built to Last, the early leaders also followed the good-to-great framework; (2) Good to Great acts more as prequel to Built to Last than as a sequel, despite being published several years later; (3) A good-to-great company becomes iconic when it accelerates its momentum in tandem with its core values; (4) The two books’ central ideas complement each other.

Collins then expands on the notion of core ideology, arguing that an enduring great company exists with purpose beyond just profit and cash flow. The values themselves don’t have to fit into predetermined criteria, but they must be clearly identified and expressed. Without a core ideology, a company can remain highly profitable—even great—but it may not be able to sustain or elevate its greatness.