Abstract: 45Systems, methods, and computer program products are described for aligning multiple images of arrays of biological materials. One method includes aligning a grid with a first image, generating grid alignment data based on the alignment of the grid with the first image, storing the grid alignment data in memory, retrieving the grid alignment data responsive to an indication to align a second image, and analyzing the second image based on the retrieved grid alignment data. In some implementations, the first image and second images are generated by scanning the same array of biological materials. The array may be a spotted array, a synthesized array, or other type of parallel biological assay.