  The globular cluster NGC 288 was previously reported to exhibit two distinct
red giant branches (RGBs) in the narrow-band Calcium (HK) and Str\"omgren b and
y band passes. In order to investigate this phenomenon further, we obtained
moderate resolution (R$\sim$18,000) spectra of 27 RGB stars in NGC 288 with the
Hydra multifiber spectrograph on the Blanco 4m telescope at Cerro Tololo
Inter-American Observatory. From these data we derive iron
($\langle$[Fe/H]$\rangle$=-1.19; $\sigma$=0.12), oxygen
($\langle$[O/Fe]$\rangle$=$+$0.25; $\sigma$=0.13), and sodium
($\langle$[Na/Fe]$\rangle$=$+$0.15; $\sigma$=0.26) abundances using standard
equivalent width and spectrum synthesis techniques. Combining these data with
those available in the literature indicates that the two giant branches have
distinctly different light element chemistry but do not exhibit a significant
spread in [Fe/H]. A new transmission tracing for the CTIO Ca filter, obtained
for this project, shows that CN contamination is the primary spectral feature
driving the split RGB. Interestingly, the CN leak in the current CTIO Ca filter
may be used as an efficient means to search for CN-weak and CN-strong stars in
systems with otherwise small Ca abundance variations.
