The results of research into patterns of change and stability in water conservation are used to draw attention to some potentially important questions for prosocial teaching in schools. The patterns emerged from a main study measuring three rounds of responses from 2,600 urban, primary and secondary students and their parents and teachers in cross-sectional and longitudinal samples over seven years and from a similar, four-year, comparative study of 600 participants in a regional area. The results tracked water conservation knowledge, attitudes, intentions, and behaviour as well as sources of information and persuasion that participants considered to have been influential in bringing them to their current level of water conservation. Similar patterns of change and stability prevailed across all data sets in both studies. Changes in student behaviour were minimally related to knowledge. Changes were best explained in two ways: stable, age-related, developmental patterns and differences across time in general community influences rather than in school-specific effects on change. For prosocial education in general, these findings raise various questions about effective delivery and about the potential role of development. It is argued that these questions, by virtue of their significance in public policy decisions, need further investigation.