This study investigates how teachers observe and assess elementary school students' foreign language performance in class and how such assessments vary among teachers. Twenty-six elementary school teachers and 23 English teachers at secondary schools in South Korea watched videotapes of 6th-grade students' group activities in English and were asked to assess the students' performance as if they were in their own classrooms. The study found that the teachers varied substantially in their overall evaluations both within and across school levels. A discussion held among the teachers after the individual assessments were completed showed that the elementary school teachers and secondary school teachers differed with respect to: (1) their views toward assessment criteria, (2) how to evaluate student confidence and motivation; and (3) how to gauge students' potential ability to communicate competently in a foreign language. Such differences between the elementary and secondary school teachers appeared to be deeply rooted in their respective teaching contexts. Using Davison's (2004) framework for analyzing teachers' beliefs and practices in teacher-based assessment, the current study suggests that both groups of teachers need to negotiate assessment criteria while paying close attention to the local context and adapting their teaching practices to fit therein. (Contains 3 tables, 2 figures and 4 footnotes.)