Society in the middle colonies was far more varied, cosmopolitan, and tolerant than in New England.  Under William Penn, Pennsylvania functioned smoothly and grew rapidly. By 1685, its population was almost 9,000.  The heart of the colony was Philadelphia, a city of broad, tree-shaded streets, substantial brick and stone houses, and busy docks. By the end of the colonial period, nearly a century later, 30,000 people lived there, representing many languages, creeds, and trades. Their talent for successful business enterprise made the city one of the thriving centers of the British Empire.

Though the Quakers dominated in Philadelphia, elsewhere in Pennsylvania others were well represented. Germans became the colony's most skillful farmers.  Important, too, were cottage industries such as weaving, shoemaking, cabinetmaking, and other crafts.  Pennsylvania was also the principal gateway into the New World for the Scots-Irish, who moved into the colony in the early 18th century. "Bold and indigent strangers," as one Pennsylvania official called them, they hated the English and were suspicious of all government. The Scots-Irish tended to settle in the backcountry, where they cleared land and lived by hunting and subsistence farming.

New York best illustrated the polyglot nature of America. By 1646 the population along the Hudson River included Dutch, French, Danes, Norwegians, Swedes, English, Scots, Irish, Germans, Poles, Bohemians, Portuguese, and Italians.  The Dutch continued to exercise an important social and economic influence on the New York region long after the fall of New Netherland and their integration into the British colonial system. Their sharp‑stepped gable roofs became a permanent part of the city's architecture, and their merchants gave Manhattan much of its original bustling, commercial atmosphere.