This study comprehensively analyzed the ERF gene family in Arabidopsis and rice. A total of 122 and 139 ERF genes were identified in Arabidopsis and rice, respectively. The gene structures, phylogenetic relationships, chromosome locations, and conserved motifs of the ERF genes were analyzed. The ERF genes in Arabidopsis were divided into 12 groups, and those in rice into 15 groups, with some groups further subdivided into subgroups. The major functional diversification within the ERF family predated the divergence between monocots and dicots, while some groups or subgroups are species-specific. The expansion of the ERF family in plants is attributed to chromosomal/segmental duplication, tandem duplication, and ancient transposition and homing. The study provides a comprehensive overview of the ERF gene family in these two plant species, which will be useful for future functional studies.This study comprehensively analyzed the ERF gene family in Arabidopsis and rice. A total of 122 and 139 ERF genes were identified in Arabidopsis and rice, respectively. The gene structures, phylogenetic relationships, chromosome locations, and conserved motifs of the ERF genes were analyzed. The ERF genes in Arabidopsis were divided into 12 groups, and those in rice into 15 groups, with some groups further subdivided into subgroups. The major functional diversification within the ERF family predated the divergence between monocots and dicots, while some groups or subgroups are species-specific. The expansion of the ERF family in plants is attributed to chromosomal/segmental duplication, tandem duplication, and ancient transposition and homing. The study provides a comprehensive overview of the ERF gene family in these two plant species, which will be useful for future functional studies.