Animal glue is the most important protein adhesive obtained from animal hides, skins, and bones through hydrolysis of the collagen. Animal glue production has long been a lucrative business in various parts of the world. This chapter discusses pretreatment and conditioning techniques including acidic, alkali, and enzymic proteolysis, which are involved during animal glue production. The extraction methods, including denaturation and thermal treatment, are also discussed. The possible improvement of pot life and moisture resistance of animal glue using chemical modification technique is presented. The application of micro-bubble technique for glue production from cow skin is also introduced.