Analyses of participation usually assume a dichotomy between 'instrumental' and 'transformative' approaches. However, this study of voluntary biological monitoring experiences and outcomes finds that they cannot be fitted into such a dichotomy. They can enhance the information base for environmental management; change participants through education about scientific practice and ecological change; lead to changes in life direction or group organisation; and influence decision-makers. Personal transformation can take place within a conventionally top-down context. Conversely, grassroots data collection can shore up the status quo and protect local interests. Partnerships between actors can provide distinct but complementary and mutually rewarding outcomes. Power is not located in a data-consuming centre, and data are not meaningless materials that leave the collector unmoved. A more dynamic model of human-nature relations is presented which connects humans and information in the participatory process.