**Preface to "Early Child Development: From Measurement to Optimal Functioning and Evidence-Based Policy"**

This textbook was first conceptualized during an invitation to create and edit a Special Issue dedicated to international child health. The Multidisciplinary Digital Publishing Institute gave me the freedom to propose a theme for the Special Issue that is of interest for a global audience. Although putting together a call for papers, editing, and contributing to a Special Issue as the only Guest Editor—during the COVID-19 pandemic—was a monumental task, I welcomed the challenge. The response from international colleagues and the quality of the papers made the Special Issue stood out. Consequently, I was invited to edit this textbook, including the content of the Special Issue entitled Early Child Development: From Measurement to Optimal Functioning and Evidence-Based Policy. The purpose of this textbook is to highlight the importance of focusing and investing in early child development. Following my clinical expertise and research interest, the guiding frameworks used in this textbook are the World Health Organization's International Classification of Functioning, Disability and Health (ICF) and the United Nations Convention on the Rights of the Child. As such, the content promotes a rights-based approach and a functioning-based approach in early child development, topics of global interest and application. As a developmental pediatrician, I am passionate about learning about the environmental factors influencing children's developmental trajectories, in particular identifying modifiable factors to promote optimal functioning of children with and without disabilities. This is crucial because early child development and overall children's developmental trajectories have long-term implications for health, functioning, and earning potential as these children become adults. Importantly, failing to reach developmental potential contributes to the global cycles of poverty, inequality, and social exclusion. In recent decades, the recognition of the close connection between the development of the child and the development of families and communities has served as the basis for national and global initiatives in health and education. Chapter 1 provides an overview of the content of this textbook, and it describes how the studies included in each chapter align with the core areas of Early Child Development, with a special focus on measurement, optimal functioning, and implications for evidence-based policy. The content of this textbook raises global awareness of the importance of a child's first years of life and the crucial role of child–environment interactions where the child lives, plays, and grows. The studies included in this textbook represent all the continents with diverse cultural and socioeconomic backgrounds. I am grateful to the international experts who generously shared information related to pivotal topics in early child development, including the need of culturally sensitive tools, successful transdisciplinary models of care, novel intersectoral frameworks, population-based data, and ongoing and upcoming environmental projects that invite positive change in practices. As such, I trust this text contributes—to the global community—novel information promoting optimal functioning in natural environments, ultimately guiding high-quality programs and evidence-based policies for young children around the world.

> **Ver ´onica Schiariti** *Editor*
