  In this article I review recent developments in near-infrared emission line
searches for star-forming galaxies at high redshift. Using the J-, H- & K-bands
we can potentially chart the history of star formation over the range 1<z<5
using the prominent rest-optical nebular emission lines alone, filling in the
"redshift desert" at z~1-3 where most common emission lines lie outside the
optical bands. Studying the rest-frame optical at z~2 also allows a fair
comparison to be made with the local Universe - the rest-optical lines are
vastly more robust to extinction by dust than the rest-UV, with the
resonantly-scattered Ly-alpha line particularly unreliable. I discuss the
recent history of near-infrared emission-line searches using narrow-band
imaging and spectroscopy, and look to the future in this era of 10-m
telescopes: such work gives us the potential to push to z>10, the next frontier
in the Hy-Redshift Universe.
