The aspirated voiceless initials (ph-, th-, kh-, and tsh-) with the lower (陽) tone classes (tone 5 to 8) in Taiwanese originated from the aspirated voiced initials (*bh-, *dh-, *gh-, *dzh-). Previous studies identified several word families comprising unaspirated and aspirated forms of the historically voiced initials in Taiwanese and other Coastal Min languages. They argued that those aspirations are causative or volitional but did not analyze the causativity and volitionality in detail. This study discovers more word families with aspiration contrast by searching through Taiwanese dictionaries. Also, this study confirms the causativity of most of those aspirations by analyzing the semantics of example sentences in Taiwanese and finds a few volitional, denominal, and deverbal cases. Furthermore, this paper infers that the causative aspirations originated from the Old Chinese causative prefix *s-, which made its following voiced obstruent initial aspirated in Coastal Min but unaspirated in Inland Min. Besides, this paper proposes a strategy of morphological instruction for reinforcing students’ understanding of causative aspiration words and causative sentence construction, which may benefit Taiwanese language education.