Abstract: The present invention relates to the areas of organic and medicinal chemistry. More specifically, the present invention is concerned with combinatorial and solid phase methods for the synthesis of diverse diketopiperazine derivatives, and the use of such methods to create libraries of diverse diketopiperazine derivatives. The present invention has application in the areas of chemical synthesis, the screening for new diketopiperazine derivatives having beneficial medical properties and the use of such screening to provide compositions and methods including diketopiperazine derivatives for treating disease.