The Induced Density of Interface States model is revisited and discussed for weakly-interacting organic semiconductor junctions. First, unreactive ‘ideal’ Au/organic interfaces are analyzed and described as a function of the organic Charge Neutrality Level (CNL) and the slope parameter S_MO specific to the case of Au: these values are similar, though not necessarily equal, to those obtained from a fit to reactive and unreactive metal/organic interfaces. Then, using the information provided by the Au/organic cases, we obtain the organic/organic screening parameters and calculate molecular level offsets without any adjustable parameter. The good agreement found between our theoretical results and experimental data for weakly-interacting metal/organic and organic/organic interfaces shows that our analysis in terms of the organic CNL and the corresponding (S_MO or S_OO) slope parameter provides a consistent and predictive description of the energy level alignment at these interfaces.