Currently, there is little information transfer between empiricists working on cooperative interactions between species (mutualism) and theoreticians who model possible scenarios for the evolution and maintenance of cooperation between unrelated individuals. Furthermore, both theoretical and behavioral approaches often fail to consider ecological parameters that influence behavior. Our goal is to present the wealth of empirical knowledge (both behavioral and ecological) on mutualistic systems in a structure that may facilitate communication between empiricists and theoreticians. We have chosen eight broad categories of mutualisms that have been intensely studied and that are relatively well understood. For each system, we assess possible states of 12 parameters that can help theoreticians to construct game structures of mutualisms that are built on current empirical knowledge. We point out how ecological variables may influence behavioral decisions in ways not identified by our parameters. Finally, we elucidate similarities between mutualistic systems with respect to game structures that may not be expected given the diversity of mutualisms with respect to ecological and evolutionary background. On the basis of these results, we promote an interactive approach with models based on empirical knowledge, amenable to further testing.