this thesis includes a study of solvatochromic molecules in the liquid and gas phases, and a study of photochromic molecules in the solid phase. the solvatochromic molecules studied are nile red, betaine 30 and its penta tert-butyl substituted analog betaine 45, 4-dmabn and its derivatives, as well as n-phenyl-benzohydroxamic acid and its derivatives. the photochromic molecule of study was the spiropyran molecule commonly known as 6-no₂ -bips, which was investigated in polymer media. calculation of the change in electronic dipole moment from the ground to the first excited state of nile red was accomplished by experimental and theoretical methods. nile red possessed a structured absorption band with two maxima, which caused a dilemma as to which absorption maximum to pair with the emission maximum for the purpose of calculating stokes shift.