In this talk I present a theoretical and experimental study of line shapes in modulation transfer spectroscopy (MTS) and electromagnetically induced transparency (EIT) for rubidium atoms. In MTS line shapes for two-level atoms and 87Rb atoms are calculated and compared with experimental results. It is found that the strong signal at the cycling transition results from the long interaction time of the atoms with laser light. I present also a diagrammatic method for EIT for ladder-type atoms. By considering the interaction routes of the coupling and probe photons, it is possible to completely discriminate between the pure one-photon and the pure two-photon resonance effects, and the effect of their combination in EIT. It is shown that the proposed diagrammatic method is very useful for the analysis of multi-photon processes in ladder-type EIT.