Abstract: Supersymmetry and extra dimension models predict the existence of gravitinos and Kaluza-Klein gravitons, stable massive particles that interact only gravitationally.  These particles are produced by late decays of WIMPs and may be the dark matter in the present universe.  Such superweakly-interacting massive particles (SWIMPs) are impossible to detect in all conventional dark matter searches due to the weakness of the gravitational interaction.  On the other hand, precise data from cosmological observations provide a promising window.  We study constraints from BBN, CMB, and diffuse photon observations.  Recent WMAP measurements of the baryon density are in good agreement with BBN predictions from Deuterium and Helium. On the other hand, the predicted abundance of Lithium exceeds observed values.  We find that late decays to SWIMPs may explain the Lithium discrepancy.