An ever-growing number of studies provide evidence for the benefits of mindfulness-based interventions within a variety of clinical and nonclinical contexts. For the field to develop and solidify, it will be essential to go beyond demonstrating clinical effectiveness and to develop an evidence-based understanding of the psychological, physiological, and neural processes that underpin the reported benefits. In our own research, we thus aim to thoroughly investigate individual components of typical mindfulness-based interventions and to pinpoint the underlying mechanisms that facilitate such positive outcomes. Towards this end, we are investigating functional and neural changes associated with attentional functions because the training and refinement of attention is at the heart of many forms of mindfulness practice. Primarily focusing on electrophysiological methodologies, data from recent randomized controlled studies will be presented. These results indicate that regular engagement with a brief mindful breathing practice for periods as short as three weeks leads to significant improvements in the neural processes underpinning different aspects of attention, confirming that attentional functions are a relevant target of mindfulness practice.