A behavioral syndrome is a suite of correlated behaviors expressed either within a given behavioral context (e.g., correlations between foraging behaviors in different habitats) or across different contexts (e.g., correlations among feeding, antipredator, mating, aggressive, and dispersal behaviors). For example, some individuals (and genotypes) might be generally more aggressive, more active or bold, while others are generally less aggressive, active or bold. This phenomenon has been studied in detail in humans, some primates, laboratory rodents, and some domesticated animals, but has rarely been studied in other organisms, and rarely examined from an evolutionary or ecological perspective. Here, we present an integrative overview on the potential importance of behavioral syndromes in evolution and ecology. A central idea is that behavioral correlations generate tradeoffs; for example, an aggressive genotype might do well in situations where high aggression is favored, but might be inappropriately aggressive in situations where low aggression is favored (and vice versa for a low aggression genotype). Behavioral syndromes can thereby result in maladaptive behavior in some contexts, and potentially maintain individual variation in behavior in a variable environment. We suggest terminology and methods for studying behavioral syndromes, review examples, discuss evolutionary and proximate approaches for understanding behavioral syndromes, note insights from human personality research, and outline some potentially important ecological implications. Overall, we suggest that behavioral syndromes could play a useful role as an integrative bridge between genetics, experience, neuroendocrine mechanisms, evolution, and ecology.