Humans have a remarkable capacity to feel and enact care for others. But this capacity is not universally expressed: decades of research have elucidated the contextual, social, cognitive-affective, and relational factors that limit the tendency to experience empathy and engage in prosocial action. Buddhist contemplative traditions have long been concerned with the alleviation of suffering and expanding the boundaries of those who we hold in our circle of care. Recent years have seen a growth of interest in contemplative approaches to cultivating compassionate responses to suffering. This dissertation explores contemplative approaches to training compassion, focusing on the question of whether we can, with volitional training, expand the boundaries of our circle of care.Chapter 1 draws on contemporary research from cognitive, affective, and social psychology to provide an integrative review of empirical studies of compassion training. I consider what constitutes compassion training and offer a summary of current meditation-based approaches. I then provide an overview of the empirical evidence for a relationship between compassion training and changes in socioemotional processes, prosocial behavior, and physiological stress responses to the perception of others’ suffering. I further address challenges in interpreting data from these studies, considering training-related mechanisms of change and how compassion-relevant processes might develop over time. I conclude by outlining key theoretical challenges for future research. Chapters 2 and 3 empirically investigate two key issues in contemplative approaches to training compassion: the generalization of training effects, and the volitional expansion of the circle of care. Leveraging EEG data collected as part of the Shamatha Project—a multimethod study of the psychobiological effects of intensive meditation retreat training—these chapters work to contribute to the understanding of the neurocognitive consequences of intensive contemplative training. Establishing whether effects instantiated through meditation training generalize to other, non-meditative states is an essential link in understanding how contemplative training may influence behavior—including responses to suffering—outside of the meditative context. In Chapter 2, I examine retreat-related changes in the resting brain. I show that rest is not a static baseline but rather indexes behaviorally meaningful effects of retreat training. Notably, the training-related changes in the resting brain observed in Chapter 2 closely mirror patterns of change observed in these same participants when they actively practiced mindfulness of breathing meditation. This offers support for the idea that changes instantiated during meditation practice may generalize to other, non-meditative contexts, providing key evidence for the generalization of meditation-related change. In Chapter 3, I explore whether brain activity recorded during compassion meditation provides evidence that contemplative training can extend the circle of care. Using microstate analysis, I first show that the general patterns of retreat-related change observed during compassion meditation are similar to those of the resting brain. This finding establishes global shifts in brain dynamics as a core consequence of intensive meditation training. I next use sequence analysis to compare temporal patterns of brain activity during compassion meditation when a close other, a difficult other, and all others are taken as the object of compassion. I hypothesize that the mental representations of these various others—reflected in the ongoing activity of the brain—should become more similar with training. I find consistent differences in microstate sequences as a function of the target of compassion. I do not, however, find any evidence that these sequences become more similar with training. Thus Chapter 3 establishes microstate sequence analysis as a viable method for distinguishing target-based differences in brain activity during compassion meditation, but does not offer evidence for the extension of the circle of care. As a whole, this dissertation grapples with how we can understand and measure the consequences of contemplative practice. The empirical studies offer two small contributions to the greater project of understanding if and how we can collectively expand our circles of care.