The emerging field of DNA computing draws from biochemistry, math and computer science to create new ways to solve problems. DNA‐based computers use combinatorial libraries of DNA strands to store information while manipulating these strands to solve problems. In order for DNA computing to be successful, these libraries must be able to be constructed in an easy and reliable manner. We have constructed libraries of 28 combinations and have developed a method for building libraries of almost unlimited size. We first assembled of an initial library (a “block”) that represents every possible combination of two sequences in five positions (five variables). Oligonucleotides were primer‐extended to create 25 possible sequences of 88‐bp. Another 3‐variable block of 62‐bp was similarly created. The blocks contained restriction sites. They were digested and ligated to create 28 combinations of 150‐bp library strands. Currently, we are verifying that each of the 28 possible strand combinations is present in the library. This library should be useful in solving mathematical satisfiability (SAT) problems. This research is supported by an NSF‐UBM Award.