Nutritional assessment has been considered as a cornerstone of nutritional diagnosis, management, intervention and dietary planning. Specific criteria, methods and procedures should be used for different age groups through a person's life cycle based on the requirements of each age group. Use of precise and accurate nutritional assessment tools and procedure to detect those who are malnourished or at risk of malnutrition will help dietitians to create an accurate dietary plan and intervention, which may help in quality of life improvement. This handbook includes the details of each assessment method for different age groups, from pregnancy to old age. It will be used as a quick, practical guide and reference for clinical dietitians. It includes dietary, anthropometric, biochemical and clinical assessments.