Collective efforts of several laboratories in the past two decades have resulted in the development of various methods for Agrobacterium tumefaciens-mediated transformation of Arabidopsis thaliana. Among these, the floral dip method is the most facile protocol and widely used for producing transgenic Arabidopsis plants. In this method, transformation of female gametes is accomplished by simply dipping developing Arabidopsis inflorescences for a few seconds into a 5% sucrose solution containing 0.01-0.05% (vol/vol) Silwet L-77 and resuspended Agrobacterium cells carrying the genes to be transferred. Treated plants are allowed to set seed which are then plated on a selective medium to screen for transformants. A transformation frequency of at least 1% can be routinely obtained and a minimum of several hundred independent transgenic lines generated from just two pots of infiltrated plants (20-30 plants per pot) within 2-3 months. Here, we describe the protocol routinely used in our laboratory for the floral dip method for Arabidopsis transformation. Transgenic Arabidopsis plants can be obtained in approximately 3 months.