Nutritional deficiencies remain a major public health concern among school-age children worldwide, particularly in low- and middle-income countries. Adequate nutrition during childhood is essential for physical growth, cognitive development, immune function, academic performance, and long-term health outcomes. Deficiencies of essential micronutrients such as iron, vitamin A, vitamin D, iodine, zinc, and folate continue to affect millions of children globally. These deficiencies can lead to impaired growth, anemia, reduced learning capacity, increased susceptibility to infections, and poor psychosocial development. This review examines the epidemiology, causes, clinical manifestations, health consequences, assessment methods, and prevention strategies for nutritional deficiencies among school-age children. Evidence-based interventions, including school feeding programs, dietary diversification, food fortification, supplementation, and nutrition education, are discussed as critical approaches to improving child health and development.