Most optimally-doped high- Tc cuprate superconductors show a magnetic excitation (known as the 'resonance') at q=(pi,pi ) whose intensity increases sharply below Tc. This excitation provides information about the superconducting gap magnitude and symmetry. It can also be used to probe the pseudogap state above Tc because it appears at the pseudogap temperature T. Remarkably, such a resonance feature has not yet been established in La2-xSrxCuO4 (LSCO). Here we propose to use the upgraded MAPS to take temperature-dependent measurements of incommensurate spin excitations in LSCO which we believe correspond to the resonance. We propose to look at two samples, optimally doped (p=0.16, Tc=38K, T ~100 K) and underdoped (p=0.125).