The book offers condensed summaries of twenty-three major models of skill acquisition and expertise development presented by leading researchers during the last half a century of classic and new research. This book presents new researchers in learning, training, cognitive sciences or education disciplines with a big picture starting point for their literature review journey. The book presents an easy t understand taxonomy of twenty-three models which can give new researchers a good bird's eye view of existing models and theories, based on which they can decide which direction to dig further. The reviews in this book are complemented with over 200 authentic sources which a researcher read for detailed and deeper dive and set the direction for further exploration. This book would also act as an essential reference for training & learning professionals and instructional designers to design research-based training curriculum to develop skills of their staff. Chapter 1 of the book elaborates on how the processes of learning, skill acquisition, and expertise development are interwoven. Chapter 2 presents a classification of various models reviewed in literature in five categories. Chapter 3 describes twelve models of skill and expertise acquisition which are represented in the form of stages. used frequently in learning, training and performance literature. The chapter also discusses the implications of each model toward developing skills and expertise of a less proficient individual to a higher level of proficiency briefly. Chapter 4 reviews practice-, time- or task-based models which are theories or models suggesting that acquisition of knowledge & skills, development of expertise and performance improvement is a function of nature of practice, amount of time spent on the task and task type. Chapter 5 presents the factor-based models, which are based on theories or models suggesting the interplay of several factors that influence the acquisition of knowledge & skills, development of expertise and performance improvement. Chapter 6 embarks on describing expert modeling-based models which are theories or models suggesting modeling an expert through elicitation or guidance for acquisition of knowledge & skills, development of expertise and performance improvement. Chapter 7 covers some newer movement toward cognition-based models which are theories or models focusing on mechanisms of cognition learning for the acquisition of knowledge & skills, development of expertise and performance improvement. Chapter 8 concludes the book by integrating views from various thought leaders to explain a famous staged skill acquisition model.