  We describe preliminary results from an ultra-sensitive, spectroscopic
emission-line survey and illustrate the challenges inherent in identifying
high-redshift LyA emitters. Our multi-slit windows technique complements other
types of emission-line surveys. Narrowband imaging surveys cover large areas of
sky but only detect much brighter objects. Longslit spectra taken along cluster
caustics yield intrinsically fainter lensed LyA emitters but probe small
volumes of space. We have observed the COSMOS deep field and a field at 15h
+00. To a line flux of a few times 10^-18 erg/s/cm^2, we found 150
emission-line sources (with no detectable continuum) among 4 masks. These
candidates are being re-observed with broad spectral coverage to determine the
line identity. To date, the interloper to LyA ratio is about 8:1. The sky
positions of the LyA candidates generally do not coincide with those of
foreground objects in ultra-deep r band or i' images -- consistent with the
presence of a strong Lyman break.
