The concept of certainty has aroused some limited interest in the theory attaching to land-use or urban planning (Booth 1996, Tewdwr-Jones 2002). What consideration it has received has mainly been in relation to planning practice, more precisely, the control of development. Why then, does the notion of certainty feature so highly in various governments’ justification of their intervention in the use of land and their regular drives to reform planning by attempting to increase it? A plan-led system, which has remained a key feature of planning regimes under jurisdictions of varying and even radical political complexion, can be justified on the ground of reducing uncertainty, resulting in fewer costly appeals and delay at the development control stage. However the plan is the provider of certainty in the rhetoric of government. This has the effect of placing a high level of importance on its details which are then subject to an increased level of scrutiny by land owners and developers with an attendant requirement on the planners to deal with an increasingly wide range of issues in greater detail. An increase in efficiency and speed of approval in one part of the planning system can therefore be off-set by an extended process of achieving the higher level of certainty at the plan-making stage. In this way, certainty, as an objective of the planning system, performs as a fulcrum in the balance of the two major components of the process. The role of certainty at the plan-making stage is rarely addressed even when considered key to the planning process. While the planning authority may wish its plans to be as sound as possible and central government assured that its current policies and ideology are addressed, there must be reservations about the way in which certainty is achieved and contained within strategic plans. Long term planning statements are predictably unreliable and this problem has sometimes been addressed by reducing their specificity but inevitably they need to include some policy content even if only as a guide to more detailed local plans. However, with the strategic content of local plans being constrained by the introduction of a standard LEP template in NSW, greater responsibility inevitably falls on the strategic plan to provide additional detail. This paper is an attempt to unravel the notion of certainty in land-use planning by engaging with other concepts such as discretion and flexibility, prescription and control, all of which have resonance in the way in which we seek to understand and operate the planning system. It mainly focuses on the situation in NSW but brief references are also made to planning regimes in the UK (now just England and Wales), the Netherlands and the United States. The material is mainly based on the principal policy frameworks directing plan-making and development assessment as they have coalesced over the past 30 years or so. It is a report of research in progress.