TESOL practitioners, especially in Asia, tend to believe that reliable assessment of students' L2 English speech can be done solely by L1 English native speakers with sufficient teaching and assessment experiences. Such a belief, however, may need to be reconsidered from a new perspective of "diversity and inclusivity." This study used data from the ICNALE Global Rating Archives, a newly compiled assessment dataset, to examine the degree of the effects of raters' L1, assessment experience, and teaching experience on their assessment of Chinese, Japanese, and Thai learners' L2 English speech. The quantitative analyses showed that (1) raters' L1 significantly influenced the assessment scores for all three learner groups, but the difference between native speaker raters and non-native speaker raters was not clear, (2) raters' assessment experience influenced the scores only for Japanese learners, and (3) raters' teaching experience did not significantly influence the assessment scores for any of the three learner groups. These findings, which cast doubt on the dependence on native speaker raters alone, suggest the need to involve a greater variety of raters in L2 speech assessment.