A study was conducted using 292 sixth-graders (aged 12) and 301 eighth-graders (aged 14) from nine comprehensive schools in Joensuu, Finland to examine the effective properties of closed and open English vocabulary tasks in individualistic and cooperative learning situations. The report is based on a larger study "Situation- and Task-Specific Motivation in Foreign Language Learning and Teaching," which investigated the relationship between trait and state motivation. The students performed three open and three closed English vocabulary tasks in three different learning situations (individualistic, cooperative, and competitive). The students' pre- and post-task appraisals and attributions were recorded by means of an on-line motivation questionnaire immediately before and after each task. Closed tasks seemed to produce more success assessments while open tasks tended to give rise to failure assessments (i.e., students are more liable to perceive themselves as failures in open tasks than in closed ones). The cooperative situation produced more success assessments than the individualistic situation. High achievers did well in both open and closed tasks, however, low achievers tended to perceive themselves as failures in the open task in the individualistic situation. Contains 45 references. (GLR)