This overview and analysis of language policy and planning (LPP) in Taiwan since the seventeenth century is written from the perspective of language ecology and uses Cooper's three-part approach: status planning, acquisition planning and corpus planning. The paper investigates how languages and their speakers have interacted with one another and with their sociocultural and political contexts, and how different policies at different times have altered the local language ecology. Three emerging factors that are changing the local ecology are further identified. As the first step to successful LPP is a detailed understanding of the local language ecology, it is hoped that the analysis presented here will provide insights for future LPP in Taiwan.