Popular interest in the observation and study of freshwater invertebrates is increasing. This book meets the needs of this growing audience of naturalists, environmentalists, anglers, teachers, students, and others by providing substantive information in easy-to-understand, non-technical language for many groups of invertebrates commonly found in the streams, lakes, ponds, and other freshwater environments of North America. Section One provides background information on the biology and ecology of freshwater organisms and environments and explains why and how invertebrates can be studied, simply and without complex equipment, in the field and the laboratory. Section Two describes nearly 100 of the most common groups of invertebrates, and for each group a whole-body colour illustration is provided along with brief text pointing out the most important features that identify members of the group. Section Three contains in-depth descriptions of the life history, behaviour, and ecology of the various invertebrate groups, and explains their important ecological contributions and relationships to humans. The Guide is broad in scope, geographically and taxonomically, and it is written at a substantive yet easily accessible level that will appeal to both novices and those with more advanced knowledge of the subject. It also contains more than 100 specially commissioned colour illustrations by the well-known scientific illustrator Amy Bartlett Wright that will greatly facilitate the easy and rapid identification of specimens.