This work discusses, from an ecophysiological perspective, how to select the trait or set of traits able to characterize in durum wheat genotype differences in yield performance under Mediterranean conditions. After a brief introduction justifying the potential contribution of ecophysiological assessment to breeding programs we discuss some practical aspects concerning evaluation of traits. In this context the advantages of evaluating integrative traits during the late stages of the crop cycle are stressed as well as the importance of the growing environment when defining the best trait or set of traits to assess. All these general recommendations are illustrated with examples of durum wheat grown in field conditions. In such context different promising tools for trait evaluation are presented.