  We present the results of an optical spectroscopic survey designed to search
for low-luminosity, "dwarf" Seyfert nuclei in a magnitude-limited sample of 486
bright, northern galaxies. Moderate-resolution spectra of exceptionally high
quality were obtained in part to detect broad H-alpha emission, similar in
character to, but much weaker than, the broad permitted lines that define type
1 Seyfert nuclei. One of the primary goals of the survey is to better quantify
the faint end of the luminosity function of active galactic nuclei. This paper
describes the subset of nuclei showing definite or probable evidence of broad
H-alpha emission. We outline the procedures for determining the presence of
this elusive spectral feature, steps for its quantitative measurement, and the
associated systematic errors. Of the 211 emission-line galaxies classified as
having Seyfert or LINER nuclei in our survey, the broad H-alpha line was
detected with confidence in 34 objects, and with less certainty in another 12.
Most of the detections are reported for the first time, and the detection rate
represents a lower limit to the true incidence of active nuclei harboring a
broad emission-line region. These statistics imply that broad-lined active
nuclei are much more common than previously believed: they exist in at least
20% of all galaxies spectroscopically classified as "active" and in more than
10% of all luminous galaxies at the current epoch.
