Many personal reports from experienced meditators exist on how subjective time slows down in meditation practice as well as in everyday life. However, hardly any empirical work exists regarding this exceptional experience. In this theoretical chapter we discuss cognitive and neural models of time perception. We aim at showing how the subjective passage of time and duration are modified by functional states of mindfulness, i.e. by attention regulation, body awareness and emotion regulation. The ability of expert mindfulness meditators to focus more strongly on sensory experiences and to be more strongly aware of feelings and of body states leads to a slowing down of time in the present moment. Moreover, as a consequence of more efficient attention regulation capacities, memory formation is enhanced which in retrospect leads to a subjective lengthening of past duration. Empirical studies concerning time perception in meditation practitioners would help to understand meditative states and at the same time would foster knowledge on cognitive-emotional as well as neural processes underlying the experience of time.