Noninvasive techniques have been developed for the assessment of various parameters in normal and diseased tissues of mice. This protocol describes the measurement of extravascular parameters, including interstitial diffusion, convection, and binding parameters, in mouse tumors. A fluorescently labeled molecule of interest is infused into the tumor interstitium, followed by imaging using single-photon microscopy or multiphoton laser-scanning microscopy (MPLSM). Fluorescence recovery after photobleaching (FRAP) with spatial Fourier analysis is performed. To measure interstitial diffusion coefficients, multiphoton FRAP is performed.