The 2013 Impact Factors are now available via Journal Citation Reports. These are the most recent Impact Factors. The 2014 metrics will become available in late July 2015. Journal Impact Factors are a proprietary measurement of journal quality based on the number of citations publications appearing in that journal have received in the last two publication years. Impact Factors are available for some 7000 journals across many fields and are published annually.
Impact Factors can be viewed through the Journal Citation Reports database available through WHSC Library subscriptions.
For questions about Impact Factors and other measurements of publication quality and impact please email Ask-A-Librarian, or check out the library webpages on Quality Indicators under the Writing and Publishing tab.