Ensuring that a building structure is stable is core to the art of structural engineering. It is a fundamental requirement of all structures. Yet experience suggests that concepts of stability (or rather instability) do not come intuitively to design engineers. This is concerning given the potential severity of an inadequate ‘stability’ system. This Guide contains parts 1 and 2 of a new four-part series. The series focuses on lateral load resisting systems: a narrow sub-set of the many types of stabilising structures but which is widely dubbed ‘the stability system’ of a building. Contained herein, Part 1 of the series gives an overview of lateral load resisting systems, introducing considerations set by actions, material characteristics, building form, function and construction. Its focus is the philosophy upon which decisions on a system can be based. Part 2 goes on to outline the specific characteristics of triangulated or ‘framed’ vertical bracing. It contains sections on each of analysis and design. The two further parts to complete the series are Part 3: Shear Walls, and Part 4: Moment Frames. These will be published as standalone volumes; each assuming the reader has a good grasp of the philosophy contained within Part 1. The series is an introduction written primarily for graduate design engineers, particularly those approaching a professional review. The content is largely applicable to all buildings, whether permanent or temporary, static or deployable, and should be considered to have international relevance.