F. Gesztesy, G. Teschl On the Double Commutation Method (33K, amslatex) ABSTRACT. We provide a complete spectral characterization of the double commutation method for general Sturm-Liouville operators which inserts any finite number of prescribed eigenvalues into spectral gaps of a given background operator. Moreover, we explicitly determine the transformation operator which links the background operator to its doubly commuted version. (Proc. Amer. Math. Soc., to appear.)