Handedness is a multidimensional phenomenon co-determined by polygenetic and developmental aspects, multifactorial influences and in some cases, pathological impact. It is important for professionals working with children, including those who are still undecided about their writing hand, to assess, analyse and understand the complexity of handedness comprehensively to prevent problems related to switched or atypical handedness. Beyond Left and Right Handedness uses a practice-based approach to handedness and systematically integrates theory, research and practice. Part I,  Theory and Research,  critically evaluates and utilises the broad spectrum of the handedness literature as a theoretical basis for the development of handedness instruments. Part II,  Assessment and Analysis,  presents diagnostic and analytical instruments developed by the author based on numerous in-depth studies and extensive clinical practice over 20 years.