This book constitutes the refereed proceedings of the 21st International Conference of the International Graphonomics Society on Graphonomics in Human Body Movement, IGS 2023, held in Évora, Portugal, during October 16¿19, 2023.The 12 full papers presented in this book together with one short paper and two invited papers were carefully reviewed and selected from 23 submissions. The conference centers around graphonomics research aimed at comprehending the processes of handwriting acquisition and execution. Moreover, it delves deeper into the impact of the writer's neural, psychological, and biomechanical conditions on the various aspects of handwriting

¿HANDWRITING LEARNING AND DEVELOPMENT.- A short review on the analysis of graphonometric evaluation in children.- Assessment of Developmental Dysgraphia Utilising a Display Tablet.- Analysis of eye movements in children with developmental coordination disorder during a handwriting copy task.- HANDWRITING ANALYSIS.- On the analysis of saturated pressure to detect fatigue.- HANDWRITING FOR EDUCATION.- IntuiSketch, a pen-based tutoring system for anatomy students.- Towards visuo-structural handwriting evaluation based on graph matching.- Copilotr@ce Put to the Crowdsourcing Test.- HANDWRITING FOR NEURODEGENERATIVE DISORDERS.- A Machine Learning Approach to Analyze the Effects of Alzheimer's Disease on Handwriting through Lognormal Features.- Feature Evaluation in Handwriting Analysis for Alzheimer's disease using Bayesian Network.- I Can't Believe It's Not Better: In-air Movement For Alzheimer Handwriting Synthetic Generation.- HANDWRITTEN HISTORICAL DOCUMENTS.- The Neglected Role of GUI in Performance Evaluation of AI-based Transcription Tools for Handwritten Documents.- Estimating the Optimal Training Set Size of Keyword Spotting for Historical Handwritten Document Transcription.- A Digital Analysis of Mozart's F-Clefs.- SPECIAL SESSION on Movement variability.- Movement Variability analysis.- SPECIAL SESSION on Lognormality.- Lognormality: an open window on neuromotor control.