We investigated the impact of self-assessment training on student achievement and on computer self-efficacy in a technology-supported learning environment (grade 9 students using Global Information Systems software). We found that self-assessment had a positive effect on student achievement, accounting for 25% of the variance across three measures. The treatment effect was as large for females as for males and for those with low initial self-efficacy as it was for those with higher scores. In addition, self-efficacy increased more in the control than in the treatment group. We interpreted the self-efficacy results to be a positive outcome of the treatment: teachers may have used self-assessment training to depress the inflated selfperceptions of some teenagers. 4Self-Assessment in a Technology Supported Environment:The Case of Grade 9 Geography Most teachers include self-assessment in their repertoires (Noonan & Duncan, 2005), particularly if they are enacting assessment reform in their classrooms. Self-assessment embodies many of the key features of assessment reform (as defined by Aschbacher, 1991;Newman, 1997;Wiggins, 1993;. For example, interpreting one"s performance using explicit criteria meets the reform objective that assessments involve higher-level thinking and disciplined inquiry. Selfassessment that makes visible the procedures, criteria and standards of assessment meets the reform goal of transparency. Negotiating differences between student and teacher appraisals addresses the reform expectation that assessments provide students with opportunities for feedback and revision during the task. A central element of assessment reform is the expectation that assessments will contribute to improved student. However, evidence of the consequential validity of self-assessment is derived almost entirely from studies of classrooms in which technology is not in high use. In this article we will present the results of a study that investigated the consequential validity of self-assessment in a technology-supported environment (grade 9 Geography).In this article we will first review research on self-assessment to demonstrate that selfassessment is a valid and reliable technique for assessing student performance, particularly in contexts in which self-assessments are used for formative rather than summative purposes; that self-assessment contributes to student achievement in regular classrooms; and that few studies of the effects of self-assessment in technology-rich classrooms are available and these produced mixed results. We will argue, from a theoretical model of the mechanisms that link self-5 assessment to achievement, that researchers need to include student self-efficacy beliefs in examining the achievement effects of self-assessment in technology-supported learning environments. From this foundation we will report the results of a study of self-assessment involving Geography students in their first high school year. Foundation for the Study Self-assessmentIn this article we will follow Klenowski"s ...