This chapter presents recent developments of multiple scattering and mesoscopic concepts in seismology. After a brief review of classical elastic wave propagation in the Earth, we focus on the scattered waves that form the tail or coda of the signal. The stabilization of vertical to horizontal kinetic energy ratios in the coda is illustrated with data from small crustal earthquakes recorded at a temporary network in California. Using a priori geological data, we show that the measurements agree very well with the equipartition principle applied to a layered elastic medium. This confirms that the formation of the coda results from the multiple scattering of elastic waves by Earth's heterogeneities. The concepts of equipartition, diffusion, and energy stabilization are carefully discussed and distinguished with the aid of numerical Monte Carlo simulations. We underline that energy stabilization occurs much earlier than equipartition because the latter concept asks for an isotropic energy flux distribution. Having established the importance of multiple scattering in the Earth we explore the role of interference in random seismic wavefields. A brief review of recent experimental and theoretical works on the weak localization of seismic waves is presented. We further explore mesoscopic concepts by demonstrating the close relations between long-time correlation of random seismic waves and the Green's function. Using data from a permanent seismic network in the Alps, we give strong experimental evidence that the correlation of seismic noise contains not only ballistic but also multiply scattered seismic waves.