Series A is concerned primarily with structures, designs, and applications of combinatorics.

[citation needed] The journal was founded in 1966 by Frank Harary and Gian-Carlo Rota.

In 2020, most of the editorial board of JCTA resigned to form a new, open access journal Combinatorial Theory.

[7] Influential articles that appeared in the journal include Katona's elegant proof[8] of the Erdős–Ko–Rado theorem and a series of papers spanning over 500 pages, appearing from 1983[9] to 2004,[10] by Neil Robertson and Paul D. Seymour on the topic of graph minors, which together constitute the proof of the graph minors theorem.

Two articles proving Kneser's conjecture,[11][12] the first by László Lovász and the other by Imre Bárány, appeared back-to-back in the same issue of the journal.