This chapter explores three thematic histories of the planning of cities in the developing Western tradition from the mid-19th to the early- 20th century. Focusing on the developing Western tradition of town planning in the larger cities of the northern hemisphere, including a number of European capitals and emerging metropolitan cities in the United States and some examples reached by emerging Western practice beyond, it roughly maps what might be termed a middle range of planning histories that are neither wholly generalized nor individually limited (Birch 2011; Ward 2002: 1–2). The three themes are structured around Bosma and Hellinga’s 1997 identification of three broadly based, thematic planning histories of the mid-to-late 19th and early 20th centuries in northern Europe, each describing a distinctive function of planning: regularization, extension, and modernism. The histories reviewed here have emerged as part of the post-1970 “new planning history” movement, and have been written principally in English. This rather experimental approach, and, for the most part, the reliance on the Anglo-Saxon and English-language traditions, means that the study is limited and constrained: a first attempt at reviewing the historiography of this interdisciplinary field, not at all the last word, nor a summary history of urban planning, but an exploration of diversity and richness.