The study is aimed at investigating the impact of self- and peer-assessment on students’ teacher efficacy and satisfaction in lesson planning at a university foreign language pedagogy course. Four self- and peer-assessment sessions for developing pedagogically sound lesson plans were held for 7 weeks. Nineteen students participated in the study. A student questionnaire was collected to see if self- and peer-assessment affected students’ teacher efficacy twice in weeks 1 and 7. In addition, in-depth interviews were conducted to understand students’ perceptions of self- and peer-assessment in terms of its benefits and room for improvement. The research revealed the findings as follows. Firstly, there was a statistically significant impact of self- and peer-assessment of lesson plans on both domains of teacher-efficacy: personal teaching efficacy and teaching outcome expectancy. Secondly, students found self- and peer-assessment satisfactory and useful when building lesson plans. Thirdly, themes for benefits of self- and peer-assessment were ‘objective perspective,’ ‘heightened insight,’ and ‘reflective thinking.’ Lastly, two themes for room for improvement in peer-assessment were ‘offering positive feedback’ and ‘working on the same period.’