Seed conditioning turns raw harvested seed into pure seed that is free of undesirable materials, safe from pests and diseases, and that which can be planted for a good stand of healthy plants of the desired crop. The cost of conditioning is a major component of the capital investment. Conditioning is the most significant process in the seed industry. It involves machines, engineering, operations, biology, physics, plant physiology and pathology, science, and business. It must be accurate, economic and practical. To make seed conditioners more efficient, this Seed Conditioning compendium was prepared. Based on real-life experiences, trials and efforts of many conditioners were compiled and distilled into a brief, easy-to-understand form.