Regardless of the terminology used, the chapters in this Handbook all converge upon a common point: epistemic cognition matters. As the modern world becomes more and more complex, it creates an ever-greater press for knowledge, something known from which people can begin to explore the questions that have not been answered, yet. Epistemic cognition is needed to sift through the vast amount of information encountered in the world to separate the justified claims from the questionable assertions, the reliable processes from the untrustworthy practices, and the availing beliefs from the recalcitrant dogma. People make myriad decisions each day based upon the results of previous acts of epistemic cognition (e.g. “I know that if I deposit money in this bank, it will be there to withdraw when I return” or “I know this finding was published in a journal I trust, so I do not need to verify it myself”). The great irony in epistemic cognition research is that the feeling of certainty, this sense of knowing what is and will happen in the world, is a necessary, frequent, often tacit everyday experience that nonetheless beguiles those who attempt to make explicit how or why that sense comes about. The research problem, and its importance, are both clear: effective epistemic cognition is necessary to navigate the complexities of the modern world, but how does it develop, what form or forms does it take, and how does it vary across the contexts in which people act?