The ECB hope the changes will benefit the England women's team
The England and Wales Cricket Board has unveiled plans to further expand women's county cricket.
An Ireland team will compete in a new six-division Championship, where 34 teams, including Minor Counties, play 10 50-over games from May to September.
In addition, there will be an inaugural Women's Twenty20 Cup competition.
Former England captain Clare Connor is the ECB Head of Women's Cricket and said: "We feel we have a structure to provide a tougher playing environment."
Sussex, who boast England players Sarah Taylor, Holly Colvin, Caroline Atkins and Laura Marsh, will play in the top division alongside Kent, who feature England captain Charlotte Edwards.
Division five is split into two regional groups, north and east, which will include the Irish team, plus south and west.
"The ECB is determined to play its part in supporting our European neighbours to play more competitive women's cricket," Connor said.
"To that end, Ireland will compete in the Women's County Championship in 2009. Scotland will again compete this year in Division Three of the women's competition, and also in the girls' Under-17 County competition.
"I am also hugely excited about the introduction of the ECB Women's Twenty20 Cup.
"There is no doubt that this is a format of the game that is here to stay and there has never been a more exciting event in the women's calendar than the ICC World Twenty20 next year.
"Our England players are desperate to play on finals day at Lord's on 21 June and the more competitive opportunities they are given to learn the art of Twenty20, the better our prospects on the international stage will be."
County Championship divisions:
Division One: Sussex, Kent, Nottinghamshire, Surrey, Berkshire, Somerset
Division Two: Lancashire, Yorkshire, Warwickshire, Middlesex, Cheshire, Essex
Division Three: Derbyshire, Worcestershire, Staffordshire, Scotland, Devon, Hampshire
Division Four: Northamptonshire, Norfolk, Hertfordshire, Cornwall, Wales, Durham
Division Five North & East: Leicestershire, Northumberland, Cumbria, Suffolk, Ireland
Division Five South & West: Wiltshire, Gloucestershire, Dorset, Shropshire, Oxfordshire