The English education system has undergone a large restructuring programme through the introduction of academy schools. The most salient feature of these schools is that, despite remaining part of the state sector, they operate with more autonomy than the predecessor schools they replace. Two distinct time periods of academy school introduction have taken place, under the auspices of different governments. The first batch was initiated in the 2002/03 school year by the Labour government of the time and was directly aimed at turning around badly performing schools. The second batch involved a mass academisation process following the change of government in May 2010 and the Academies Act of that year and resulted in increased heterogeneity of new academies. This paper compares the two batches of introduction with the aim of getting a better understanding of their similarities and differences. To do so, we study what types of schools were more likely to change to academy status in the two programmes, and the impact of this change on the quality of new pupil enrolments into the new types of school. Whilst we do point out some similarities, these are the exception rather than the norm. For the most part, our analysis reveals a number of marked dissimilarities between the two programmes in terms of both the characteristics of schools that become academies and the subsequent changes in intakes. Additional tables are appended. [This paper was produced as part of the Centre for Economic Performance's Education and Skills Programme.]