I will discuss millimeter wavelength techniques for probing two key periods in the early history of the universe: the inflationary epoch and the epoch of reionization. I will talk about two experiments in particular SPTpol and TIME-Pilot. SPTpol is a polarization-sensitive camera designed to measure the polarization of the cosmic microwave background (CMB) deployed on the 10 meter South Pole Telescope (SPT) in January 2012. I will present our recent results from the 100 square degree survey (the first year of data) focusing on the high signal-to-noise measurement of the E-mode and temperature-E-mode correlation CMB power spectra, and B-mode power spectra, and measurements of the gravitational lensing potential. The *T*omographic *I*onized Carbon Intensity *M*apping *E*xperiment (TIME-Pilot) is a new millimeter-wavelength imaging spectrometer that leverages CMB instrument technology to probe the EoR. This novel cryogenic instrument is a pathfinder for a new technique for studying the EoR through intensity mapping of the 157.7 um ionized carbon ([CII]) emission line. Specifically it is designed to detect [CII] clustering fluctuations and test the predicted [CII] amplitudes of faint emission from the earliest dwarf galaxies. The TIME-Pilot instrument will be sensitive to a wavelength range of ~200 - 300 GHz with R = 100, which will allow us to measure the redshifted 157.7 um [CII] line from z of 5 to 9, key redshifts for probing the EoR. It will also robustly detect CO clustering at low z (~1-3). [CII] intensity mapping offers a unique way to measure faint sources, which will be difficult to detect individually with JWST and ALMA. This method is also complimentary to other intensity mapping experiments such as 21-cm instruments that measure neutral matter rather than an ionized medium during the EoR. Measurements from TIME-Pilot will test the viability of the [CII] intensity mapping technique and a detection of the [CII] signal would set a strong foundation for building more sensitive line intensity mapping instruments for both ground- and space-based platforms.