Differential scanning calorimetry (DSC) and Raman spectra are reported for NaNO3 bulk and for NaNO3 confined in porous silica with pore radii, r(p)=2.5, 5, 10, 20 nm. Raman spectra are also;given for a 6 M solution of NaNO3. The melting transition for the confined NaNO3 exhibits a 1/r(p) dependence where r(p) is the pore radius for r(p)>5 nm. No melting transition is observed for NaNO3 confined in 2.5 nm pores. Above this pore size, their appears to be a deviation in the melting, transition dependence on r(p). The internal modes observed in the Raman spectra for the confined material are in agreement with those of the bulk solid except for a feature observed on the low frequency side of the upsilon(1) band. The external TO mode observed at 100 cm(-1) and the librational mode at 175 cm(-1) for NaNO3 both decrease in intensity and broaden as r(p) decreases and both bands disappear at r(p)=2.5 nm. An additional peak at 70 cm(-1) not observed in the solution or bulk NaNO3 spectra appears in the spectra of confined NaNO3 and increases in intensity as r(p) decreases. We assign this band to a new phase of NaNO3 which is stabilized by the surface hydroxyl groups of the porous silica. For NaNO3 confined in pores, r(p) less than or equal to 2.5 nm, we suggest that NaNO3 exists as disordered aggregates.