This paper elaborates on implications of Barry W. Boehm's Spiral Model of software development. The paper notes that the Spiral Model presents a compelling view of software development, evocatively represented by a visual image that appeals strongly to intuition, and notes that the view and image have motivated and justified a range of important views of how software development should be done. This paper enhances and elaborates on the intuitions by supplementing them with a definition of the Spiral Model that is enunciated in terms of a rigorously defined language. The rigorous enunciation and accompanying alternative visual depiction are then used to provide clarification and formalization of some of the clearly-indicated elaborations of the Spiral Model. Both the Waterfall Model of software development and the Scrum agile method are presented as possible elaborations of the Spiral Model. Still other elaborations are indicated. Similarities in the visualizations of these development approaches suggest some underlying similarities in the approaches themselves, suggesting the potential value of effective process visualizations. The breadth of these elaborations is also used to suggest how the Spiral Model seems to provide a strong focus on some of the quintessential aspects of what comprises effective software development.