Rituals transform citizens into presidents and princesses into queens. They transform sick persons into healthy ones, and public space into prohibited sanctuary. Shamanic rituals heal, legal rituals bind, political rituals ratify, and religious rituals sanctify. But how exactly do they accomplish these things? How do rituals work? This is the question of ritual efficacy, and although it is one of the very first questions that people everywhere ask of rituals, surprisingly little has been written on the topic. In fact, this collection of 10 contributed essays is the first to explicitly address the question of ritual efficacy. The authors do not aspire to answer the question 'how do rituals work?' in a simplistic fashion, but rather to show how complex the question is. While some contributors do indeed advance a particular theory of ritual efficacy, others ask whether the question makes any sense at all, and most show how complex it is by referring to the sociocultural environment in which it is posed, since the answer depends on who is asking the question, and what criteria they use to evaluate the efficacy of ritual. In his introduction, William Sax emphasizes that the very notion of ritual efficacy is a suspicious one because, according to a widespread 'modern' and 'scientific' viewpoint, rituals are merely expressive, and therefore cannot be efficacious. Rituals are thought of as superficial, 'merely symbolic,' and certainly not effective. Nevertheless many people insist that rituals 'work,' and the various positions taken on the question tell us a great deal about the social and historical background of the people involved. One essay, for example, illuminates a dispute between 'materialist' and 'enlightenment' Catholics in Ecuador, with the former affirming the notion of ritual efficacy and the latter doubting it. In other essays, contributors address instances in which orthodox religious figures (mullahs, church authorities, and even scientific positivists) discount the efficacy of rituals. In several of the essays, 'modern' people are suspicious of rituals and tend to deny their efficacy, confirming the theme highlighted in Sax's introduction.