Conservation reintroduction aims to establish an organism into an area from where it has disappeared or was extirpated. Monitoring is essential to identify the factors that underpin successful establishment and persistence of a self-sustaining population. The Great Bustard (Otis tarda) is globally threatened and became extinct as a breeding species in the United Kingdom (UK) in 1832. Trial releases began in 2004 to reintroduce the Great Bustard to the UK based on the release of captive-reared chicks transported from a source population in Russia. The aim of this research was to investigate the factors influencing the establishment of a founder population of Great Bustards in the UK. In Chapter 1, I set the context of the reintroduction science and management in the world today and explore the issues surrounding it. Chapter 2 sets the baseline by which to measure the Great Bustard reintroduction project using the first five years of releases (2004 – 2008). Estimating vital rates and modelling population growth, I show that low recruitment to the founder population is a limitation for establishment. Chapters 3 and 4 investigate post-release survival and dispersal, both important variables in population establishment. By modelling individual post-release survival I show that earlier date of release can improve survival and could be used to improve recruitment. Conversely, post-release dispersal had mixed implication for the management of the reintroduced population. Surviving Great Bustards incorporated the release site into their annual range and as their breeding site. However, the birds had traversed large areas reducing our ability to monitor and control the environment of individuals. In Chapter 5, the research focus moves from the reintroduction project to an examination of the impact of disturbance and conspecific attraction (presence of conspecifics positively influences the movement of individuals) in habitat selection in a small extant population of Great Bustards. I show that the spatial distribution of display sites is influenced by anthropogenic disturbance; however, the number of males attending the display sites is influenced by the abundance of female conspecifics. The management implications of this result are that the attraction to conspecifics is an important factor in habitat selection. Finally, in Chapter 6, I discuss project limitations, potential interventions and identify future areas of research.