It took place in July and August, with 36 teams taking part: 33 county teams plus Wales, Ireland and the Netherlands.
Sussex Women won the Twenty20 Cup, beating Berkshire Women in the final, achieving their first T20 title.
The tournament ran alongside the 50-over 2012 Women's County Championship.
[1] Teams played matches within a series of regionalised divisions, with the winners of the top divisions progressing to semi-finals and a final.
The winners of each Division 1, and the best-performing second-place team, progressed to the semi-finals.