The discussion of four major theoretical traditions associated with the initiation of a migration flow. ... is intelligent and persuasive. ... The analytical treatment of the selected regions is useful and generally enhances one's understanding of the migration processes in each. ... The authors speculations are refreshingly forward-looking and worth reflecting upon regardless of one's predispositions toward theory. ... the language is direct, the theoretical discussion eschews unnecessary jargon, neologisms are kept to a minimum, and the extensive summaries of the relevant bodies of literature are cogent. ... the volume is useful as a single source where many of the most influential migration theories are treated with clarity. ...those interested in having a well-organized and analytically valuable thumbnail sketch of the migration subsystems in five world regions will find plenty to chew on.