Of the several pathways by which vitamin A and its derivatives can degrade, the present study is concerned with those leading to the formation of anhydrovitamin A. Results indicate ( a ) anhydro formation does not occur readily with vitamin A alcohol in the absence of a strong catalyst such as hydrogen chloride, ( b ) the reaction proceeds at a significant rate for solutions of the acetate in both alcoholic and hydro-alcoholic systems, ( c ) the conversion of the acetate to the anhydro form is much more rapid in the presence of water than in its absence, and ( d ) formation from the acetate does not occur in ether or hydrocarbon solvent in the absence of catalytic agents. Catalytic behavior of hydrogen chloride, perchloric acid, and acetic acid were also studied. The results on experiments made with pyridine and sodium hydroxide as possible inhibitors are also presented.