Business practices have and will continue to greatly influence and determine the shape and viability of the built environment. Traditional practices have continued to use non renewable and polluting resources such as fossil fuels, and these are rapidly becoming unviable and unacceptable within the built environment. As an alternative to these traditional practices, concerned building practitioners are applying best practice initiatives in the-belief that these produce sustainable outcomes.   The research titled ‘A study of the Lithgow New Government Office Development; Using Best Practice to Deliver Sustainable Developments’ is based on the hypothesis that applying building industry’s best practice initiatives can deliver sustainability within the built environment. This hypothesis assumes links between the applied practices, the outcome achieved and sustainability. This research tests this hypothesis with a single ‘critical’ case project; the recently constructed Lithgow Government Office Building (GOB) Development, and against a theoretical framework that defines sustainability.  The GOB Development is a best practice example procured by a long lived and socially responsible organisation, government organisation - the Department of Commerce. This organisation adopted and applied new government policies along with best practice initiatives to produce a new benchmark – an award wining, trend-setting, seemingly sustainable development. The industry successes of the GOB Development made this a suitable single case study, one that was most likely to fare better than any other development procured at that time and by other means.   The research conducted provides an insight and understanding into all the different factors during the procurement of the GOB project and highlights how these influenced the eventual built outcome and determined whether sustainability would be attained. This research assessment is seen as a crucial step in understanding the many limitations of best practice and thereby enabling the building industry’s progression towards achieving sustainability within the built environment. The potential insight that can be gained from this research can enable the relationship between practice and theory to be better understood, and thereby provide the means to influence all future built outcomes. It is believed that such insight can encourage building practitioners and organisations to adopt and apply best practice initiatives as a means to achieve sustainability within the built environment