This Springer essential provides an overview of current research on the topic of left-handedness and brain asymmetries. In addition to basics of assessing left-handedness and brain asymmetries, it also explores their evolution, development, and their study in the animal kingdom. Other focal points include research on the relationship between left-handedness and cognitive functions, as well as the topic of handedness and sports. The essential is rounded off with a discussion on the topic of relearning handedness and a discourse on altered asymmetries in various patient groups.