One of the most significant impacts of the educational reforms introduced since 1988 has been the broadening of senior management in primary schools. The increased accountability and workload placed upon school management led first to the greater involvement of the deputy head and, more recently, to the creation of a leadership scale to both attract and reward other senior managers in schools. This thesis will look at the emergence of assistant heads onto that leadership scale. Through the use of job descriptions, questionnaires, interviews and a case study the functions that assistant heads are performing in primary schools will be examined and their opinions, attitudes and beliefs about their work will be considered. What emerges in this study is that the assistant heads are carrying out many significant leadership and management tasks in their primary schools. It also appears that there are three broad types of assistant headship. The first is quasi-assistant headship, where the assistant head's role is indistinguishable from a deputy head role. The second type is the subordinate assistant headship role where the post is clearly below that of a deputy head. The final type is the niche assistant head who has one clear area of significant responsibility in the school. The thesis concludes that the patterns of assistant headship are varied and that it will take time before a more consistent view of assistant headship is established in terms of the exact roles undertaken in schools and the pay levels that are appropriate with this new form of senior management.