Mindfulness is based on focusing attention to present moment and observing present moment experiences in a non-judgmental and accepting way. Mindfulness has been applied as a therapy method in Western psychotherapy practice for almost thirty years. While mindfulness stems from Eastern contemplative practices, a number of studies had investigated the psychological processes underlying mindfulness. Some of these studies focused on explaining the change mechanisms through which mindfulness-based interventions have their therapeutic effects. Meta-cognition, emotion regulation, attention regulation and interoceptive exposure have been suggested as change mechanisms involved in mindfulness based therapies. The notion explaining mindfulness as a meta-cognitive information processing asserts that the decentering involved in mindfulness decreases the effects of maladaptive meta-cognitive beliefs. The incremental effect of mindfulness on emotion regulation is another proposed effect mechanism in mindfulness-based interventions. This view suggests that mindfulness supports emotional tolerance and adaptive emotion regulation. The present-focused attention is regarded as a fundamental component of mindfulness. In studies investigating the effects of mindfulness on attentional processes, relationships have been found between mindfulness and the components of executive attention. It has also been proposed that interoceptive exposure technique and mindfulness operate through a similar therapeutic mechanism since mindfulness involves orientation towards all negative and positive subjective experiences. A number of views have been proposed regarding the relation between mindfulness and cognitive and emotional processes and the findings supported the effects of mindfulness on these processes. This is an important step towards explaining mindfulness on an operational level and increasing the effectiveness of mindfulness-based interventions.