The problem of free vibrations of bonded single lap joints in composite, shallow circular cylindrical shells or shell panels is investigated. The shallow circular cylindrical shell adherends are considered to be made of dissimilar, orthotropic materials adhesively bonded by an in-between, very thin, yet flexible adhesive layer. In the theoretical formulation, a first-order shear deformation shell theory is employed. The complete set of shallow shell equations, in combination with the adhesive-layer equations, is first reduced to a governing system of first-order ordinary differential equations in the state vector form. Then, the resulting equations are integrated by the modified transfer matrix method (with interpolation polynomials and/or Chebyshev polynomials) and the natural frequencies and the modes of the lap joint system are obtained. It was found that the hard and the soft adhesive-layer elastic constants significantly influence the natural frequencies of the shallow shell bonded lap joint system. Also, the effects of some other important parameters on the natural frequencies and the mode shapes are presented.