Psychologist Barbara L. Fredrickson is widely credited with providing some of the strongest empirical evidence that positive emotions—as subtle and fleeting as they are—drive human resilience, build enduring personal resources, and create the passion-fueled habits that define healthy lifestyles. Her work also demonstrates why certain moments of positive emotional uplift matter more than others, illuminating the very foundations of meaning, transcendence, and love. Positive Emotions presents Fredrickson's groundbreaking research, tracing the arc of her career across five successive scientific breakthroughs. Each of the book's five sections opens with Fredrickson's stories, both personal and scientific, that paved the way to each successive breakthrough. Her stories feature her mentors, her community of scientific peers, her students, her serendipitous discoveries, as well as her motivations for sharing her discoveries outside of academia for lifelong learners seeking evidence-based paths to happiness. Reflecting on a career that has thus far spanned four decades, Fredrickson also shares lessons learned along the way regarding scientific methods and career development and candidly conveys for early-career scholars what she'd do differently if she were starting out today. Each section culminates by reprinting excerpts from three key articles that Fredrickson curated to best illustrate the scope of her and her teams' contributions. Taken together, these fifteen key scientific contributions solidify positive emotions as the tiny engines that drive human flourishing.