Calculations indicate that the thermal stress resistance for diamond is significantly higher than for other materials, suggesting that diamond films may inhibit damage to optical components in laser systems. To assess this possibility we have begun to study laser-induced damage in diamond films. We have measured laser damage thresholds of free-standing diamond film windows, diamond films deposited on silicon substrates, and bare silicon substrate. Polycrystalline diamond films were deposited using a dc plasma-enhanced chemical vapor deposition process. As expected, the free-standing diamond films showed a high laser damage threshold. Melting or dielectric breakdown induced by laser radiation may be the damage mechanism. The film/substrate combination had a damage threshold lower than the calculated value, which is attributed to film stress and conditions of film deposition.