This introduction provides a basic description of the Anthropology of Smartphones and Smart Ageing (ASSA) project, including the project’s range of field sites, methods, and ethics. I compare this project with prior comparative studies in the anthropology of ageing. I also discuss certain other findings of the ASSA project as they relate to the ASSA researchers’ re-conceptualisation of the smartphone and our work on mHealth. I then consider how an anthropological approach to comparison differs from that of other disciplines, partly through examining methods of comparison found within the articles in this Special Issue. In particular, I contrast the idea that anthropologists can compare data regarded as commensurable because of a standardisation in how they were collected, to a view that anthropologists mostly do not collect commensurable data at all; in which case, perhaps anthropologists are best at making comparison at the level of implied causation, sometimes developing a spectrum of field sites where implied causation can itself act as a parameter of difference.