This paper studies total factor productivity (TFP) in Thai agriculture to provide better empirical evidence on the TFP measure and the factors influencing it. It employs time-series data at an aggregate level over the period 1970-2006 for both crops and livestock, individually, using the conventional growth accounting framework. The TFP measures are then used to investigate their determinants using the error correction modeling technique. The results confirm the general expectation from previous studies that TFP makes an important contribution to output growth and that agricultural research plays an important role in determining TFP in both the crop and livestock sectors.