  Thanks to the unnaturally small value of the QCD vacuum angle $\bar\theta <
10^{-10}$, time-reversal ($T$) violation offers a window into physics beyond
the Standard Model (SM) of particle physics. We review the
effective-field-theory framework that establishes a clean connection between
$T$-violating mechanisms, which can be represented by higher-dimensional
operators involving SM fields and symmetries, and hadronic interactions, which
allow for controlled calculations of low-energy observables involving strong
interactions. The chiral properties of $T$-violating mechanisms leads to a
pattern that should be identifiable in measurements of the electric dipole
moments of the nucleon and light nuclei.
