This paper presents a multi response decision tree (DT) approach to find the process conditions that yield products with desirable quality characteristics (QCs). We propose several criteria aggregation functions to convert responses (QCs) into an aggregated value. DT modeling is applied on the resulting aggregated values to decide on the process levels. Decision rules obtained separately for each QC can help in predicting the levels of QC values at these process levels thereafter. © 2011 IADIS.