  The production of $\eta$ and $\eta^{\prime}$ mesons in photon- and
hadron-induced reactions on free and quasi-free nucleons and on nuclei is
reviewed. The extensive database on $\gamma N \to \eta N$, for both proton and
neutron targets, is described in detail and its implications for the search for
$N^{\star}$ resonances much heavier than the dominant $S_{11}(1535)$ discussed.
Though less is currently known about the production of the $\eta^{\prime}$ or
of $\eta\pi$ pairs, these also offer tantalizing prospects in the search for
the missing isobars. The more limited data available on pion-induced production
are still necessary ingredients in the partial wave analysis discussed.
  The production of the $\eta$-meson in $pp$ and $pn$ collisions shows once
again the strong influence of the $S_{11}(1535)$ isobar, which is in contrast
to the relatively weak behaviour seen near threshold for $\eta^{\prime}$
production. This difference is reflected in the important final state
interaction effects of the $\eta$ in nuclei that may even lead to this meson
being "bound" in some systems. The evidence for this is reviewed for both
$\gamma A$ and $p A$ collisions. The inclusive photoproduction of $\eta$,
$\eta^{\prime}$, and $\eta\pi$ pairs from nuclei provides further information
regarding the production mechanism and the interaction of the $\eta$ and
$\eta^{\prime}$ with nuclei and the $\eta\pi$ pairs may even allow access to
low mass $\eta A$ systems that are forbidden in direct single-meson
photoproduction.
