Light can be confined efficiently in the high quality factor (Q), small volume whispering-gallery-modes observed in spherical dielectric microresonators. The properties of these modes allow laser action to be obtained in Erbium doped glass spheres. After a brief introduction to the physics of the whispering-gallery modes, we will describe experiments on the lasing properties of microspheres. Then, we will present results on wavelength shifts due to temperature induced by the pump power or by coupling with an external cavity. We will finish with new experiments associated with tailoring of the WGMs and effects due to the coupling between resonators.