England overcame an improved performance from South Africa to comfortably win the second Twenty20 by six wickets at Worcester.
Having made 111 in Thursday's opening-game defeat, South Africa posted 148-6.
Anneke Bosch top-scored with 61 in a century stand with fellow opener Lara Goodall.
But the visitors slumped from 102-0 after teenager Alice Capsey took Goodall's wicket in her first over in international cricket.
Katherine Brunt then became England's leading wicket-taker in international T20s when she bowled Laura Wolvaardt in the final over for 21.
While it was a significant improvement on the batting performance at Chelmsford in the first T20, England completed another convincing win with an over to spare.
Sophia Dunkley continued her aggression at the top of the order with 23 from 15 balls, Danni Wyatt made 39 and Nat Sciver top-scored with 47 before she was run out.
Sciver was standing in as captain for the injured Heather Knight, who missed out with a hip injury less than a week before the start of the Commonwealth Games.
Victory meant England extended their lead to 12-2 in the multi-format series. The final T20 takes place at Derby on Monday at 18:30 BST and is live on BBC Two.
Improvement, but not enough for South Africa
South Africa's batting has failed to fire throughout the white-ball leg of the series, the void left by power-hitter Lizelle Lee's retirement seeming to grow with each game.
It remains a problem at the top of the order, as despite Bosch and Goodall's improvement, they still only managed to reach 34-0 at the end of the opening powerplay.
But they showed fight and grit - something that had previously been missing.
Despite the slow start, they grew in confidence and accelerated, setting a platform for the likes of Sune Luus, Chloe Tryon and Mignon du Preez.
But two generations intertwined as Brunt and 17-year-old Capsey - who was just 10 days old when the former made her international debut - took their milestone wickets.
Leg-spinner Sarah Glenn also took two wickets to stall South Africa's momentum and they failed to reach the 160 mark that they would have been aiming for.
The gulf between the sides remains stark, as Dunkley and Wyatt had the confidence to attack from the offset, the former continuing her incredible form by smashing 18 from the third over before being caught going for one six too many.
Wyatt looked set to lead England home before she was dismissed by a fantastic diving catch from opposing skipper Luus in the outfield.
But England were 51-2 after the powerplay, the back of the chase already broken, which allowed Sciver to play array of creative shots before she was unfortunately run out backing up at the non-striker's end with just nine more runs needed.
