Abstract : This paper provides an overview of the aspectual organization of Ersu (southern Qiangic, Tibeto-Burman), as spoken in Zela Township in Ganluo County (Sichuan, China). It uses data collected using tense-mood-aspect questionnaires in combination with traditional narratives. In contrast to previous descriptions (Sun 1982, 1983; Liu 1983; Zhang 2013), we argue for a system in which the basic distinction between perfective and imperfective aspect is expressed by lexical-derivational means: verbal stems and directional prefixes. Other aspectual distinctions (including experiential, change of state, progressive, continuous) are encoded grammatically (verbal particles). For most particles, the expression of aspect is tightly interwoven with evidentiality. Through numerous illustrative examples, the paper provides a detailed description of the meaning and use of prefixed and unprefixed verb stems and aspectual and evidentiality particles.