Science museums, science centers, zoos, and aquariums (MCZAs) constitute major settings of science learning with unique characteristics of informal science education. Emphasis will be given to the analysis of four specific characteristics of MCZAs that seem relevant for educational research and practice, namely, conditions of mixed motives and goals, staged popular science, and impact of physical layout, as well as the role of social exchange and participation. By doing so, we focus on the consequences of these characteristics for the learning processes and outcomes of visits of MCZAs. We show that outcomes encompass not only knowledge acquisition in a narrower sense but also changes in interest and beliefs.