Although the earliest record of a commercial theatre at Hong Kong can be traced back to 1856, the Tongzhi period (1862-1874) witnessed an unprecedented development of Chinese opera theatres in the Colony. Between 1865 and 1870, three new commercial theatres were established within six years, reflecting the rapid growth of local demand of entertainment and the flourishing of Chinese/Cantonese opera industry. Such demographic and economic changes in the second half of the 19th century were brought about by two major historical events: Taiping Movement (1850-1864) in China, and the discovery of gold mines in North America and later in Australia. The arrival of new migrants, finance, business, and job opportunities to Hong Kong were the social and economic forces leading to the prosperity of the commercial theatre business. Containing three main sections, this paper narrates the social history of commercial theatres of late Qing Hong Kong in a concentric way: the socio-economic environments outside the theatres, the social origins and behaviors of audience in the commercial theatres, and the operatic performances and genres exhibited on the stage. A central issue is how the economic boom of Hong Kong in the "era of the Pacific" reshaped the operatic landscape of the Colony, bringing about the emergence of a new urban market of Chinese/Cantonese opera other than Canton in southern Guangdong.