Abstract: I will discuss how the next generation of CMB and Large Scale Structure (LSS) experiments can uncover information about the primordial Universe. I will review the observational signatures of the initial conditions and explain how they are connected to the physics of Inflation. I will then highlight recent techniques that combine CMB and LSS measurements to probe velocity fields at cosmological distances, serving as one of the most sensitive probes of initial conditions. If time allows, I will also discuss how to improve neutrino mass measurements by characterizing the properties of cosmic reionization using the CMB as a backlight.