The harmonic oscillator is a useful starting point for understanding many intermolecular interactions, and it successfully predicts many properties. However, anharmonic terms in the interaction potential are responsible for several observed phenomena. This review summarizes our recent experimental investigations of three thermal properties of molecular solids that result from anharmonic intermolecular interactions, viz. thermal expansion, Grüneisen parameters, and thermal conductivity. Key words: anharmonicity, thermal expansion, Grüneisen parameter, thermal conductivity.