Assessment has shifted from assessment of learning to assessment for learning. Self-assessment and peer assessment therefore appear to play more important roles as they encourage students to critically reflect on their own and their peers' learning progress and performance. Although self-assessment and peer assessment of written language performance have been widely explored, assessment of spoken language, especially in presentation skills, is under-explored. Additionally, students' peer assessments are found to be different from teachers' assessments (De Grez, Valcke, & Roozen, 2012), with this possibly due to the lack of training. This study aimed to investigate whether in-service teacher participants, with experience in marking students' performance, would be able to undertake self-assessment and peer assessment effectively in comparison to the teacher's assessment. The study also intended to explore participants' perceptions of self-assessment and peer assessment of English presentation skills. The participants were 14 in-service teachers teaching their native language at different levels, ranging from primary to tertiary, who were also studying English as a foreign language. The research instruments were scoring rubrics and an online questionnaire. The data were analysed by Pearson's correlation coefficients, means and standard deviations. The results revealed that in-service teachers could perform better in peer assessment. The study's discussion provides fruitful implications for language assessment.