The American Journal of Psychiatry (AJP) has few peers when it comes to the impact its articles have on the field, according to a new ranking.

AJP is now the psychiatric journal with the second highest impact, according to a new ranking by the research firm Thomson Reuters. The publication-impact factor is a numerical ratio that compares the number of articles published by a journal in a two-year period with the number of citations of those articles during the same time frame.

This ranking moves AJP up from third place to second among the 117 journals in the psychiatric field. The journal with the highest impact is Molecular Psychiatry. It also means that AJP is ranked among the top 100 scientific, technical, and medical journals that Thomson Reuters ranks. AJP's impact factor places it at number 89.

AJP also retains its number-one ranking as the psychiatric journal whose articles are the most frequently cited. In 2007 and 2008 there were more than 42,000 citations of its published articles, about 8,200 citations more than the next-ranking psychiatric journal.