The propensity to focus inward – internal attention – is fundamental to human mental life and internally-directed cognition (IDC) such as mindwandering and (mal)adaptive self-reflection. Yet, our understanding of the mechanisms through which internal attention shapes IDC is limited. We argue that our capacity to predict and model (mal)adaptive IDC may be significantly facilitated through understanding the complexity and dynamics of how internal attention interacts with other cognitive processes from which higher-level IDC emerges. We therefore introduce the Attention-to-Thoughts (A2T) model – a dynamic systems theory and computational model of internal attention in IDC. Through the model we aim to, first, conceptually and computationally define momentary states of this dynamic system; and, second, to simulate and predict differential temporal trajectories of this dynamic system through which IDC emerge. Through a series of experimental simulations, we explore how A2T may be used to better understand how internal attention selection is expressed from moment-to-moment; how the dynamic system of internal attention unfolds by documenting how, as a function of contextual demands for focused attention, internal attentional selection iteratively transacts with working-memory and emotion; and, in turn, how higher-level maladaptive IDC (e.g., repetitive negative thinking, cognitive dyscontrol) emerges from temporal trajectories of the dynamic system of internal attention. Finally, we highlight key conceptual, computational and methodological directions for the study of internal attention, IDC and related phenomena (e.g., mindfulness).