One of the most pressing of ecosociological concerns is the search for ways in which to engage the public in the monitoring and debate about global climate change. Phenology, the study of the appearance or seasonal timing of natural events such as flowering, migration, and reproduction, is rapidly emerging as an important tool for fostering environmental awareness and participation. Increasingly, professionals are turning to the diaries of 18th and 19th century amateur phenologists in an attempt to gauge biological trends of our modern warming world and at the same time are encouraging groups of contemporary citizen “scientists” to continue undertaking such measurements. This chapter will review and critically comment on these approaches from both a scientific and sociological perspective and offer an expanded view about what might constitute an “ecosystem service” for human welfare.