Yoga is an ancient spiritual tradition that has retained some of its original elements while also showing a clear evolution. Historically, yoga consisted mainly of stationary meditative practices for spiritual purposes; over time, yoga has seen an increase in movement-based practices for both spiritual and non-spiritual reasons. Previous research has shown that yoga, in its many forms, can lead to psychological benefits. The goals of the current research were to understand the relationship between yoga and several constructs that may influence yoga’s effects, to determine how length of practice influences these relationships, and to identify the specific contribution of movement – also called physical postures (Sanskrit: asanas). Two studies were conducted. Study 1 was a cross-sectional design that compared psychological (depression, anxiety, stress, mindfulness, emotion dysregulation, interoceptive awareness, and self-compassion) and spiritual (spiritual intelligence) self-report measures among long-term, intermittent, and non-practitioners of yoga. Long-term practitioner scores reflected greater psychological and spiritual health compared to the other two groups on all measures, except depression, anxiety, and stress. Mediation analyses revealed that the relationship between yoga experience and emotion dysregulation was dependent on interoceptive awareness and spiritual intelligence in one model, and mindfulness and self-compassion in a second model. Study 2 was a randomized-control trial that compared participation in an eight-week asanas-based Hatha yoga practice with an education group who learned about the history and philosophy of traditional yoga. Five self-report measures (depression, anxiety, stress, mindfulness, emotion dysregulation, interoceptive awareness, and self-compassion) and an attentional task were completed before and following each program. Compared to their pre-scores, the yoga group’s post-scores were higher on all measures except attention. The yoga group had higher scores on stress and interoceptive awareness compared to the education group. Mediation analyses revealed that mindfulness, interoceptive awareness, and emotion dysregulation mediated the relationship between yoga program and depression, anxiety, stress, and/or emotion dysregulation in six different models. Taken together, these two studies suggest prominent roles for these constructs in explaining yoga’s mechanisms, corroborate findings that these are attainable benefits in even short-term interventions, and demonstrate that asanas-based yoga is associated with psychological improvements.