A fastening system comprises a side grid, a pullout guide, and multiple fastening elements fixed on the pullout guide, by means of which the pullout guide is fixed in a formfitting manner on a horizontal rod of the side grid, wherein the horizontal rod has a middle section extending in a longitudinal direction and two angled end sections, which are each fixed on an upright of the side grid, wherein at least a front fastening element has at least one contact surface inclined in relation to the vertical for contact on the middle section of the rod, and at least one rear fastening element has a contact surface inclined in relation to the vertical on the middle section of the rod, wherein an essentially V-shaped receptacle is formed on the front fastening element, which encloses the front angled end section of the rod from above. Furthermore, the invention relates to a method for installing a fastening system.