This report has been prepared under contract to the Ministry for the Environment. It aims to help users understand the new soft-bottom variant of the Macroinvertebrate Community Index (MCI), and how it and other members of the "family" of MCI biotic indices can best be used to measure the health of New Zealand streams. This is not a formal national guideline or protocol, nor is it a complete description of biotic indices or the design of monitoring programmes. The views expressed are based on the experience of the authors in developing and using these indices. We hope you will find our suggestions useful and that the guidance we provide will stimulate discussion, promote greater use of the macroinvertebrate community [Community: all of the different kinds of macroinvertebrates living in the same place.] in the assessment of hard-bottomed and soft-bottomed streams, and lead to a greater consistency of approach among users of the MCI.