A method is provided for determining a ranking score for an image or group of related images among a plurality of images accessible by a search engine, such that the ranking score is usable to determine the order in which the images are presented in the results of a search conducted by the search engine. The method comprises monitoring the number of times the image (or the images in the group of related images) is presented for viewing by predetermined users in the results of searches conducted by the search engine. The level of active interest shown by the predetermined users in the image or images presented for viewing in the search results is then monitored, for example by determining the number of times that users select a thumbnail of the image for viewing on an enlarged scale. Finally a ranking score is assigned to the image or images based on the monitored level of active interest as a proportion of the number of times the image or images are presented for viewing by the predetermined users. This then enables an identified set of images to be ordered in such a manner as to take into account the ranking scores of the images, in order to enable users to access the images that they require more quickly and conveniently.