Meditation research has expanded exponentially over the past few decades, establishing consistent effects of improved well-being; however, little work has focused on experimentally investigating the underlying mechanisms of how meditation improves well-being. Additionally, there is a consensus in the field to address sources of bias and the role of placebo and demand effects by implementing more rigorous methods. Therefore, with these motivations in mind, the goal of this dissertation is to provide confirmatory and exploratory evidence on the effects of meditation in a series of single-session, randomized controlled trials. Chapter 1 establishes the base effect by comparing the effects of a mindful Meditation to an informational Control, which were both labeled as a “relaxation exercise” to participants, on several measures of well-being. Then, this effect is re-examined by taking into account the mechanistic role of two aspects of a person’s internal state: expectations, or how much a person expects to improve from a session of meditation, and thought valence, or how positive or negative a person’s thoughts were during the meditation. Chapter 2 aims to replicate and expand upon these results by comparing Meditation and Control to isolated components of meditation: Breath (slow breathing), Mind (meta-awareness), and Detachment (meta-awareness and detachment). Again, the mechanistic role of internal experiences is assessed. After elucidating key components and potential mechanisms of meditation, Chapters 3 and 4 aimed to explore potential sources of bias or inflated results. Using only the Meditation Intervention, Chapter 3 investigates the causal role of expectations by manipulating participant knowledge of the intervention in two ways: presence/absence of the Label “meditation”, and presence/absence of a Placebo statement. Finally, Chapter 4 addresses exploratory questions on meditation efficacy and equity. Conclusively, this study (1) quantifies observable changes in well-being due to a single session of meditation, while considering the mechanistic role of internal experiences; (2) clarifies which components of meditation are necessary or sufficient to improved well-being within a single session, again looking at the role of internal experience; (3) determines how much a label and demand effects contribute to a potential placebo effect within meditation interventions; and (4) evaluates the efficacy and equity of meditation as a treatment with exploratory analyses.