This volume explores how imperial powers established and expanded their empires through decisions that were often based on exaggerated expectations and wishful thinking, rather than on reasoned and scientific policies. It explores these exaggerations through the concepts of El Dorado, utopias and dystopias - undertakings based on irrational perceived values - in case studies from across the sixteenth to the twentieth centuries, and incorporates imperial traditions including Scottish, British, French, German, Italian and American. Various colonial spaces are considered, from the Mediterranean, Middle East, Africa, Australia, Asia and the Americas, and in doing so, the contributors offer new insights into the nature of imperialism and colonial settlement. The book does not try to explain the broader motives of imperialism and colonial settlement, but instead focuses on understanding these ventures, in which unrealistic arguments were made that justified imperial and colonial interventions and envisaged rapid success. Such cases proved illusory and sometimes disastrous, and thus serve as deconstructive tools for demystifying imperial policy. These bad decisions were often twisted and turned to justify them differently, and there was a great reluctance to admit a flawed or failed policy, let alone reverse it. Imperial expectations and realities will prove useful to academics and students at all levels, and in a variety of specialisms within History, but particularly in comparitive imperialism and colonialism, and Policy Studies.