Champions Southern Vipers will open the defence of their title this weekend against Loughborough Lightning in the Rachael Heyhoe Flint Trophy. The competition returns for its second season with eight sides competing.
The 50 over competition is named in honour of former England captain Baroness Heyhoe Flint who died in 2017.
Eight sides competing for the title
Central Sparks, South East Stars, Northern Diamonds, Western Storm, Sunrisers and Thunder are the other sides taking part.
There will also be a new T20 tournament featuring the eight sides which will begin on 26th June. 56 matches will be played in the summer across the two formats.
In the inaugural final at Edgbaston last September Vipers defeated Northern Diamonds. A total of 41 players signed full time professional domestic contracts for this summer.
Teams will face each other once during the league stage with the side who finishes top advancing straight to the final. The second and third placed teams will play off, with the winner progressing to the final.

Sparks missed out last time up
Last seasons tournament was split into two groups with Central Sparks missing out on a place in the final.
This season Sparks will look once again to the bulk of runs from Eve Jones who hit 334 runs last campaign. The reliable Marie Kelly should also contribute once again with the bat.
Spin could work in Sparks favour with the excellent leg spinner Anisha Patel available. Off spinner Georgia Davis is also a player who will take wickets.
Bryce sisters on fire for Lightning
The Bryce sisters shone for Lightning last campaign, with captain Kathryn picking up 14 scalps and Sarah hitting 395 runs.
Lightning will also have the added bonus of having England opener Tammy Beaumont available for the opening three matches.
England internationals Katherine Brunt, Nat Sciver and Lauren Winfield-Hill will feature for Northern Diamonds this season.
21-year-old batter Sterre Kalis a player to watch out for. Veteran Jenny Gunn will also bring a wealth of experience to the side.

Leading wicket taker Hartley back for Thunder
North West Thunder will be skippered by Alex Hartley, who was the leading wicket taker last year with 11 dismissals. The side also boast the leading ranked T20 spinner in Sophie Ecclestone available for the opening salvos.
South East Stars have available 16-year-old batter Alice Capsey once again. The youngster is a name to look out for after scoring 141 runs last year for Stars. England player Sophie Dunkley is in the squad but may get an international call up at any time.
18-year-old Chloe Brewer, who scored over 100 runs in just two innings last year, is a youngster to admire. Looking likely to be a big name of the future.
Can Vipers dominate once again this season?
Southern Vipers dominated last season’s competition by winning all seven matches convincingly. This season the competition looks a lot stronger will all sides adding to their squad with key players.
Vipers will be looking towards the excellent Georgia Adams, who also captains the side. Adams had an astonishing season last year by scoring 500 runs at an average of over 83.3.
Coached by former England captain Charlotte Edwards, the southern based side will have promising bowler Lauren Ball available. The 20-year-old seamer has certainly impressed the England selectors and could well move up to the international stage this summer.
Along with a fine blend of experience and youth in the shape of 16-year-old seamer Freya Kemp and 17-year-old Finty Trussler, Vipers will feature heavily again.
Much improvement needed from Sunrisers
For Sunrisers, last season was one to forget having lost all six of their matches. The side will be captained by wicket keeper Amara Carr. Batter Grace Scrivens has been in fine form for Kent this season.
On paper Wester Storm look very strong. Featuring Heather Knight and England World Cup winner Anya Shrubsole, they will be there or there abouts. Shrubsole only featured once for the side last term but expect more appearances this campaign.
Rachael Heyhoe Flint Trophy fixtures
May
29: Northern Diamonds v Central Sparks (Headingley), Western Storm v Thunder (Bristol), Sunrisers v South East Stars (Chelmsford), Southern Vipers v Lightning (Southampton)
31: Lightning v Northern Diamonds (Kibworth), Central Sparks v Western Storm (Edgbaston), South East Stars v Southern Vipers (Beckenham), Thunder v Sunrisers (Chester)
June
5: South East Stars v Western Storm (The Oval), Sunrisers v Northern Diamonds (Cambridge), Southern Vipers v Central Sparks (Hove)
6: Thunder v Lightning (Chester)
12: Northern Diamonds v South East Stars (Headingley), Lightning v Sunrisers (Loughborough), Central Sparks v Thunder (Worcester), Western Storm v Southern Vipers (Taunton)
September
10: Northern Diamonds v Western Storm (Riverside), South East Stars v Lightning (Beckenham), Sunrisers v Central Sparks (Northwood), Thunder v Southern Vipers (Sale)
12: Northern Diamonds v Thunder (Riverside), Central Sparks v South East Stars (Worcester), Western Storm v Lightning (Bristol), Sunrisers v Southern Vipers (Chelmsford)
18: Lightning v Central Sparks (TBC), South East Stars v Thunder (Beckenham), Western Storm v Sunrisers (Bristol), Southern Vipers v Northern Diamonds (Southampton)
22: Play-off – 2nd v 3rd (TBC)
25: Final – 1st v Winner play-off (TBC)