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We construct small-$x$ evolution equations which can be used to calculatequark and anti-quark helicity TMDs and PDFs, along with the $g_1$ structurefunction. These evolution equations resum powers of $\alpha_s \, \ln^2 (1/x)$in the polarization-dependent evolution along with the powers of $\alpha_s \,\ln (1/x)$ in the unpolarized evolution which includes saturation effects. Theequations are written in an operator form in terms of polarization-dependentWilson line-like operators. While the equations do not close in general, theybecome closed and self-contained systems of non-linear equations in thelarge-$N_c$ and large-$N_c \, \& \, N_f$ limits. We construct a numericalsolution of the helicity evolution equations in the large-$N_c$ limit.Employing the extracted intercept, we are able to predict directly from theorythe behavior of the quark helicity PDFs at small $x$, which should haveimportant phenomenological consequences. We also give an estimate of how muchof the proton's spin may be at small $x$ and what impact this has on theso-called "spin crisis."  Based on JHEP 1601 (2016) 072 (arXiv:1511.06737), arXiv:1610.06197 andarXiv:1610.06188.

Helicity Evolution at Small x: Summary of Recent Developments