spectroscopic samples (e.g., @Newman08 [@Rahman15]. At least two independent methods to measure $N(z)$ for the tomographic shear samples will be required to ensure no systematic photo-z biases exist; these methods can therefore serve as useful checks on each other.

Here we describe the initial stage of what we are calling the Complete Calibration of the Color-Redshift Relation (C3R2) survey, designed to fill out the color space of galaxies with secure redshifts to the *Euclid* weak lensing depth. By doing so, the empirical  relation obeyed by galaxies can be constrained with sufficient accuracy to meet the cosmological requirements of *Euclid*. The spectra will also be of significant value for the LSST and *WFIRST* calibrations, which will be more difficult than for *Euclid* due to the greater photometric depth of those surveys (Hemmati et al, 2017, in prep). We estimate that $\sim$40 Keck nights in total (or their equivalent) could achieve the fidelity required to meet the cosmological requirements for *Euclid*, when combined with extensive existing spectroscopy.

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This paper gives an overview of the C3R2 survey and presents results from the 2016A semester, which constituted the first five nights of observing. All 2016A observations were 