We have extended our evolutionary synthesis models for star forming regions to the γ-ray domain. We obtain the light-curves of γ-ray line emission due to radioactive decay of stellar nucleosynthesis products, such as 26 Al, 60 Fe, or the e- e+ annihilation line as well as the evolution of the kinetic energy from massive stars. We present the correlation of these lines with the ionizing flux produced by massive stars and some preliminary predictions about the Cosmic Ray production in star forming regions. We show that the predicted γ-ray line observations combined with others multi-wavelength measurements can efficiently constrain the age of a stellar population, and help to identify the primary nucleosynthesis sources of the radio-isotopes.