Some of the factors that contribute to the present extended durations for the design and construction of nuclear power plants are reviewed and an attempt is made to place in perspective the causes for increased project durations over those experienced in the 1960s. The following basic causes are identified: expansion and instability of regulatory activities; increased complexity and scope of engineering design and Increased material quantities and field labor manhours as a result of increased plant size. Experience has demonstrated that all the benefits of scale in plant size have not been realised. With an increase in plant size, it should be expected that the engineering per kilowatt (kW) and the material per kW would drop. Actually there has been an increase which can be attributed primarily to escalations in the regulatory requirements applied to the design. Significant engineering and construction rework has resulted from these escalations during the engineering and construction phases. Industry has been unable to standardise or stabiise its own product and procedures to the extent desired because of this instability in the licensing process and requirements. As a result of this atmosphere of changes and delays, and the growth of administrative controls and surveillance, the productivity of technical and craft personnel has suffered. To measure what could be accomplished to shorten project durations, a basic critical path logic was tested against current experience, a hypothetical case in which there is no licensing process, and a second hypothetical case where previously approved designs were accepted so that the licensing process did not impact the duration. As might be expected, the two hypothetical cases result in essentially identical overall durations. A review of projects designed and constructed under current licensing conditions shows that the licensing process adds approximately three years to the schedule during the capital intesive period after award of the reactor contract. If pre-award extensions due to early planning and site reviews are added to this, the licensing process adds approximately four to five years to a project. The steps toward shortening and improving the confidence in predicting the duration for engineering and construction should proceed in the following sequence: first reasonable stabiisation of the licensing process and requirements for design and construction must be established. Utilities can then depend on this firm base to plan and obtain financing with reasonable assurance that they will meet their objective, and the supporting technical and manufacturing industry can then gear up in a commercially competitive manner with a level of standardisation and methods that would lead to a shorter, more predictable duration for its work. Enforcement of measures to stabiise licensing requirements is thus a prerequisite to shortening project durations and to effective standardisation in the industry