What do you mean? It predicted the Top and Charm quarks, the W and Z bosons (and their masses), and many other phenomena.
We know the Standard Model isn't a complete theory or a "grand unified theory" though because there are too many empirically determined constants in it, and because it doesn't adequately explain all known particle physics.
We know the Standard Model isn't a complete theory or a "grand unified theory" though because there are too many empirically determined constants in it, and because it doesn't adequately explain all known particle physics.