Background: The ecology of physical education is created through the interaction of three task systems: managerial task system, instructional task system, and the student social system. Within the ecological framework tasks are presented and task development is influenced by concepts such as ambiguity, risk, and accountability. Teachers' and students' perceptions of assessment tasks have been examined to some extent in physical education; however, they have not been investigated through an ecological lens. Purpose of study: The purpose of this study was to examine middle school students' and their teacher's perceptions of assessment through an ecological lens in order to investigate how assessment influenced both the teacher's and the students' agenda in the classroom. Setting: The research took place in a suburban middle school located in the western part of Massachusetts. Participants: Participants were an intact class of 36 seventh-grade students and their teacher. Research design: Qualitative case study. Data collection and analysis: Data were collected in four ways: (a) videotaped record of each lesson, (b) field notes, (c) formal interviews using a semi-structured interview guide and (d) documents. Field notes and interview data were inductively analyzed using constant comparison. Categories were developed and examined for common elements that ran throughout and tied them together. Themes were then extracted from these categories. Data were selectively coded for examples that illustrated the themes. Results: Three main findings are reported. First, students' perceptions of assessment were influenced by the ambiguity of what was being assessed and the lack of risk associated with their level of performance on the assessments. Although ambiguity was present, there was little to no risk because students were not held formally accountable by a grade exchange for assessment tasks. Second, since the assessments were not used as a form of formal accountability (i.e., not linked to a grade) the students did not value assessment. Furthermore, the teacher did not value assessment tasks because she was not held accountable to assess student learning. Finally the student social system impacted students' perceptions of assessment. The students wanted to have fun and many believed assessments were not fun, rather they were boring. Students also perceived that working with their friends to do assessments resulted in more effort because students wanted to work and socialize with their friends, as well as perform the skills correctly in front of their friends. Conclusions/recommendations: Specific recommendations for practice include designing assessments that are implemented in the context of the activity. Assessments may be more effective as well as meaningful to students if physical educators are able to design assessments that incorporate students' agendas of working with friends and having fun. Future research should be conducted at other educational levels to further ascertain the role of assessment tasks in the ecology of physical education at these levels.