ABSTRACT:  This paper presents a comprehensive account of the discourse particles in colloquial Singapore English (SE), considering their etymology in the light of both structure and sociohistory. While the object of many studies, mostly focusing on their meaning and use, and generally recognised as coming from Southern Chinese languages, the establishment of the origins and evolution of SE particles has not before been attempted. The thrust of this paper is thus twofold: (i) it outlines the linguistic ecology of Singapore over the decades and proposes a framework involving three ages in which different languages are recognised as dominant, influencing the feature pool in the evolution of SE, and (ii) it identifies the most likely sources of SE particles, through (a) a systematic comparison of the forms and functions of SE particles with particles from the substrates, including, in particular, their original tone, and (b) recourse to sociohistorical facts to support the linguistic postulation. I suggest that in an early era Bazaar Malay and Hokkien contributed the particles lah, ah and what, and Cantonese in a later age provided lor, hor, leh, meh and ma, inclusive of tone. This argument highlights issues interesting for contact dynamics and new varieties of English.