Privately owned by the Macao Chamber of Commerce, the Octagonal Pavilion Library was the first free Chinese library service as well as the most used Chinese public library in Macao from its establishment in 1948 until the late twentieth century. With a total surface area of 1,130 square feet, it is possibly the smallest library in the world. Despite its diminutive size, its educational and cultural impact on the community make it unique. Its relationship to “the foreign-Chinese divide,” to Ho Yin (Macao’s most important twentieth-century historical figure), and to other libraries in Macao are of particular interest. Its architecture, classification system (centered on the Three People’s Principles), and nontechnical operations in the current technical environment also make it a meaningful library service case study.