We report the absorption and photoluminescence (PL) properties of dilute InPN layers grown by liquid phase epitaxy. All samples were characterized by high resolution xray diffraction at room temperature. The band anticrossing model accounts very well for recent experimental results obtained on different samples. Our results indicate that a maximum amount of0.2% nitrogen has been incorporated in the material with a band gap lowering consistent with expectations. Our theoretical results provide a good agreement with the available experimental data.