This commentary reflects on the articles in this Special Issue. The appearance of this group of articles underscores the important idea that a major target of mindfulness practice is on emotion. Transformation in trait affect is a key goal of all contemplative traditions. This commentary addresses several key methodological and conceptual issues in the empirical study of mindfulness. The many ways in which the term "mindfulness" is used in the articles in this Special Issue are noted, and they include its reference to states, traits, and independent variables that are manipulated in an experimental context. How the term "mindfulness" is conceptualized and operationalized is crucial, and for progress to be made it is essential that we qualify the use of this term by reference to how it is being operationalized in each context. Other methodological issues are considered, such as the duration of training and how it should be measured, and the nature of control and comparison groups in studies of mindfulness-based interventions. Finally, the commentary ends with a consideration of the targets within emotion processing that are likely to be impacted by mindfulness. This collection of articles underscores the substantial progress that has occurred in the empirical study of mindfulness and it is a harbinger of a very promising future in this area.