Think Green is a natural sequel of our former Think Blank book. Think Blank targets the application of analytical procedures compatible with requirements of trace analysis and microwave-assisted sample preparation is a strong ally for reaching these goals. By adopting a Think Blank approach we decrease the volumes and concentrations of reagents for improving blanks and consequently for reaching better limits of detection. Well, if we reduce the amounts of reagents we are by extension going green. In this sense, requirements for greening sample preparation procedures aiming trace analysis are proposed and discussed here. For instance, have you thought about energy needed for promoting and keeping the reaction system heated? What about reaction conditions for attaining efficient digestions? Have you thought about generation of too reactive or dangerous products? How about risks to the analyst and to the environment? Let us think again. In this book modern strategies for developing green digestions are presented and we demonstrated how available instrumentation allows us to reduce the use, to substitute critical reagents, and even how to recycle and reuse reagents. We believe there is a need to keep an eye on blank procedure performance and another eye on green strategies for meeting goals searched for up-to-date and ease-of-use procedures fully applied for trace analysis.