Given the importance of assessment in language education, the main purpose of this study was to investigate the effects of interactionist and interventionist Dynamic Assessment (DA) on EFL learners' perfectionism, willingness to communicate (WTC), and foreign language anxiety (FLA). The participants were 166 pre-intermediate EFL learners in two public schools and a language institute. They were divided into three groups and given three separate questionnaires to measure their perfectionism, WTC, and FLA before the treatment. During 14 sessions, groups A and B received instruction using interactionist DA and interventionist DA, respectively. Group C was instructed conventionally. After the treatment, they were given the same three questionnaires. The participants' responses to the questionnaire items were turned to scores on a Likert-like scale. The collected data were analyzed using one-way ANCOVA. The results showed no significant differences among the groups in terms of their perfectionism and willingness to communicate. Although there was no significant difference between the interactionist and interventionist models of DA, they were both significantly more effective than the control condition on learners' FLA. This means that DA, regardless of its type, has a facilitative role in reducing anxiety in a foreign language setting. These findings can have implications for teachers, students, and material developers.