We have demonstrated a protocol for purifying functional Sec23-24 complex from rat liver cytosol. Because the rat liver Sec23-24 complex is highly susceptible to proteolysis, we have noted several modifications which have allowed us to overcome the problem of degradation. If care is taken to prevent proteolysis, this procedure typically yields 2 mg of functional complex. The Sec23-24 complex can then be used to study Sar1 GTP hydrolysis in the Sec23 GTPase activation assay. Additionally, Sec23-24 can reconstitute ER vesicle formation in the presence of Sar1 and Sec13-31, allowing for the identification of novel proteins or compounds that affect cargo export.