An integrated nodal model was described for the 1-D multigroup diffusion equation. The finite-difference method (FDM) and the diffusion theory nodal method (DTNM) were used to solve the diffusion equation. The partial currents were used at the nodal interfaces and the diffusion theory boundary conditions were applied at the external boundaries. The use of the partial currents at the nodal interfaces was essential to the development of the integrated nodal model. The interface partial currents allow the program user to choose any combination of the two aforementioned methods of solution, to change models while the calculation continues, or to use both methods simultaneously. Different cases of a sample problem were investigated. The results showed a perfect flux match at the nodal interfaces between the two methods of solution. The flux match at the interfaces was the result of using the partial currents.