  We discuss the properties of quarter-BPS local operators in four dimensional
${\cal N}=1$ supersymmetric Yang-Mills theory using the formalism of
holomorphic twists. We study loop corrections both to the space of local
operators and to algebraic operations which endow the twisted theory with an
infinite symmetry algebra. We classify all single-trace quarter-BPS operators
in the planar approximation for $SU(N)$ gauge theory and propose a holographic
dual description for the twisted theory. We classify perturbative quarter-BPS
operators in $SU(2)$ and $SU(3)$ gauge theories with sufficiently small quantum
numbers and discuss possible non-perturbative corrections to the answer. We set
up analogous calculations for some theories with matter.
