We report on the vibrational population and orientational relaxation dynamics of 1-methylperylene in the series of normal alkanes n-pentane through n-decane, n-dodecane, and n-hexadecane. We find that both the vibrational population relaxation time constant, T-1, of the 1-methylperylene 1370 cm(-1) mode add the orientational relaxation time constant(s), tau(or), depend sensitively and nonlinearly on the aliphatic chain length of the n-alkane solvent. The data show that the two relaxations are sensitive to solvent local organization on approximately the same length scale and stand in contrast to our recent reports on the relaxation dynamics of perylene in the same n-alkane solvents (J. Phys. Chem. 1994, 98, 6436; 1994, 98, 9411), where the operative length scale of T-1 relaxation was found to be substantially shorter than the length of the perylene molecule. We understand these differences in the context of the different polar nu-nu coupling processes utilized by perylene and 1-methylperylene. The rotational diffusion data for 1-methylperylene indicate that the dominant reorientation axis of the chromophore changes with solvent aliphatic chain length.