For the biharmonic problem, we study the convergence of adaptive C 0 -Interior Penalty Discontinuous Galerkin (C 0 -IPDG) methods of any polynomial order. We note that C 0 -IPDG methods for fourth order elliptic boundary value problems have been suggested in [9, 17], whereas residual-type a posteriori error estimators for C 0 -IPDG methods applied to the biharmonic equation have been developed and analyzed in [8, 18]. Following the convergence analysis of adaptive IPDG methods for second order elliptic problems , we prove a contraction property for a weighted sum of the C 0 -IPDG energy norm of the global discretization error and the estimator. The proof of the contraction property is based on the reliability of the estimator, a quasi-orthogonality result, and an estimator reduction property. Numerical results are given that illustrate the performance of the adaptive C 0 -IPDG approach.