<p>The National Certificate of Educational Achievement (NCEA) is New Zealand’s main national qualification for senior secondary school students. A key feature of NCEA is that it allows for more than half of students’ final NCEA grades to be assessed by teachers during the school year through school-based assessment, known as internal assessment. This key role of teachers in awarding qualifications is likely to have an impact on their conceptions of assessment, conceptions of assessment that are not necessarily fixed. In turn, conceptions can influence teaching practice and are likely to have an impact on how teachers implement internal assessment. This thesis uses an explanatory sequential, mixed methods design to investigate a group of economics and accounting teachers’ conceptions of assessment, their practices in relation to NCEA internally-assessed standards, and the influences on those practices. G.T.L. Brown’s (2006) Teachers’ Conception of Assessment Abridged (TCoAIIIA) Inventory was used to investigate the participants’ conceptions of assessment, and interviews were conducted to probe their internal assessment practices and reasons for those practices. The quantitative data were analysed using confirmatory factor analysis which showed an inadmissible fit to G.T.L. Brown’s (2006) model. A subsequent exploratory factor analysis revealed partly similar and partly different dimensions in the data, compared with those previously reported in other studies using the TCoAIIIA. Qualitative data were thematically analysed and when the qualitative and quantitative data were considered together, greater similarities with G.T.L. Brown’s model emerged. Participants revealed four overarching conceptions of assessment: assessment is for learning; assessment is for qualifications; assessment is for accountability; and assessment is detrimental. This finding has reinforced the view that teachers’ conceptions of assessment are ecologically rational in that a distinct conception that probably relates to the role participants play in assessing for NCEA emerged. Despite this role, participants also adhered to the conception that a primary function of assessment is to improve students’ learning; furthermore, they did not support the use of assessment results as a measure of school quality. An implication of this finding is a belief that promoting a school-accountability use of assessment results is likely to be counter-productive to students’ learning. The qualitative findings revealed a complex set of beliefs and practices towards implementing the internally-assessed component of NCEA, and that beliefs were only one influence on teachers’ internal assessment practices. Teachers had to balance their beliefs with the systemic realities of NCEA and their school’s policy requirements, and articulated a tension between the improvement and accountability conceptions of assessment. Moderation processes, procedures and policy encouraged teachers into a cycle of safe rather than innovative internal assessment practice, which means that the original vision for NCEA internal assessment is yet to be realised. There are implications of this finding for professional development, leadership of assessment, and initial teacher education. One such implication is a requirement for professional development that would provide teachers with successful, innovative internal assessment practices, rather than the present approach which focusses on the reliability of marking. Schools’ management needs to take a greater role in leading and encouraging pedagogically sound internal assessment, rather than focussing primarily on agreement rates with NZQA moderators. Initial teacher educators could also introduce student teachers to effective internal assessment practices and to encourage such practices. In addition, attempts to change teachers’ assessment practices need to consider existing conceptions of assessment because beliefs have an impact on practices and may need to be challenged. While there is debate about whether beliefs change practice or vice versa, one cannot be changed without considering the other.</p>