In this study, the relationship between crystallization rate and surface chemistry of polyhedral oligomeric silsesquioxanes (POSS) in poly(lactic acid) (PLA)/POSS nanocomposites was investigated. Four different kinds of POSS particles having different chemical structures were used. The composites were processed in a Xplore micro-compounder at a screw speed of 100 rpm and 180C barrel temperature. The POSS content was varied as 1, 3, 7 and 10 wt%. Common kinetic models such as Avrami, Ozawa and Dobreva and Gutzow were used to determine the non-isothermal crystallization behaviour of PLA/POSS nanocomposites by using the thermal data obtained from differantial scanning calorimetry (DSC). The morphology during the crystal growth was investigated by a polarized optical microscope (POM) equipped with a hot-stage. Thermodynamic work of adhesion approach was adopted using the experimentally determined surface energies to investigate the interfacial interactions between POSS particles and PLA. A strong correlation was obtained between interfacial chemistry and the nucleation rate in PLA/POSS nanocomposites. It was found that the polar interactions are the dominating factor which determines the nucleation activity of the POSS particles. Keywords: PLA, POSS, nanocomposites, non-isothermal crystallization kinetic, interfacial interactions Acknowledgement: This study is granted by The Scientific and Technological Research Council of Turkey (Project No: 111M514).