  Understanding the chemical processes during starless core and prestellar core
evolution is an important step in understanding the initial stages of star and
disk formation. This project is a study of deuterated ammonia, o-NH$_2$D, in
the L1251 star-forming region toward Cepheus. Twenty-two dense cores (twenty of
which are starless or prestellar, and two of which have a protostar),
previously identified by p-NH$_3$ (1,1) observations, were targeted with the
12m Arizona Radio Observatory telescope on Kitt Peak. o-NH$_2$D J$_{\rm{K_a}
\rm{K_c}}^{\pm} =$ $1_{11}^{+} \rightarrow 1_{01}^{-}$ was detected in 13
(59\%) of the NH$_3$-detected cores with a median sensitivity of
$\sigma_{T_{mb}} = 17$ mK. All cores detected in o-NH$_2$D at this sensitivity
have p-NH$_3$ column densities $> 10^{14}$ cm$^{-2}$. The o-NH$_2$D column
densities were calculated using the constant excitation temperature (CTEX)
approximation while correcting for the filling fraction of the NH$_3$ source
size. The median deuterium fraction was found to be 0.11 (including 3$\sigma$
upper limits). However, there are no strong, discernible trends in plots of
deuterium fraction with any physical or evolutionary variables. If the cores in
L1251 have similar initial chemical conditions, then this result is evidence of
the cores physically evolving at different rates.
