Applying a recently developed method for measuring the level of specialization over time for a selection of library and information science (LIS)-core journals seems to reveal that Journal of the Association for Information Science and Technology (JASIST) is slowly transforming into a specialty journal. The transformation seems to originate from a growing interest in bibliometric topics. This is evident from a longitudinal study (1990–2012) of the bibliometric coupling strength between Scientometrics and other LIS-core journals (including JASIST). The cause of this gradual transformation is discussed, and possible explanations are analyzed.