A new link invariant is derived using the exactly solvable chiral Pott
s model and a generalized Gaussian summation identity. Starting from a
general formulation of link invariants using edge-interaction spin mo
dels, we establish the uniqueness of the invariant for self-dual model
s. We next apply the formulation to the self-dual chiral Potts model,
and obtain a link invariant in the form of a lattice sum defined by a
matrix associated with the link diagram. A generalized Gaussian summat
ion identity is then used to carry out this lattice sum, enabling us t
o cast the invariant into a tractable form. The resulting expression f
or the link invariant is characterized by roots of unity and does not
appear to belong to the usual quantum group family of invariants. A ta
ble of invariants for links with up to eight crossings is given.