Tagged synthetic oligomer libraries

An encoded library of compounds comprising:

• a solid support;
• a plurality of copies of a compound directly bound to said support, said compound having a first reactive group selected from the group consisting of amino groups, carboxyl, hydroxyl, and phosphate groups and wherein any additional reactive groups of said compound that are capable of interfering with compound synthesis or identifier tag addition have been suitably protected;
• one or more first identifier tags, each tag being directly bound to said support, said tag having a second reactive group selected from the group consisting of amino groups, carboxyl, hydroxyl, and phosphate groups and wherein any additional reactive groups of said tag that are capable of interfering with compound synthesis or identifier tag addition have been suitably protected, wherein said identifier tag is different than said compound, and
• wherein said tag identifies the compound bound to said support or records a step in a synthesis of said compound;
• and
• a substance in contact with said support selected from the group consisting of a building block having a third reactive group, a second identifier tag having a fourth reactive group, an activator group, and a solvent, wherein said third reactive group of said building block and said fourth reactive group of said second identifier tag are independently selected from the group consisting of amino groups, carboxyl, hydroxyl, and phosphate groups and wherein any additional reactive groups of said building block or said second identifier tag that are capable of interfering with compound synthesis or identifier tag addition have been suitably protected.