Substantial innings from Alex Wakely, James Middlebrook and Steven Crook put Division Two leaders Northants in control on the second day of the LV= County Championship match with Gloucestershire at Bristol.
Wakely led the way with 88 as the visitors - boosted for the second week running by an abundance of lower-order runs - ran up 404 all out in reply to 192.
Middlebrook made 62 and Crook 53, while Will Gidman returned 4-109 to finish as the pick of Gloucestershire’s attack.
The hosts were left with an awkward period to bat before the close and lost skipper Michael Klinger for a single in moving to 34 for one, still 178 runs behind.
Northants began the day on 107 for three and Rob Newton soon set about adding to his score of 14, pulling a ball from Alex Gidman over fine-leg for six.
Newton had moved brightly to 39 by the time he was caught at backward point by Jack Taylor off Benny Howell.
Wakely, unbeaten on 23 overnight, looked in good touch, but Andrew Hall received a life on 18 when dropped by Chris Dent at second slip off David Payne.
Hall had 27 to his partner’s 80 at the interval, but could add only a single in the afternoon session before falling lbw to Will Gidman.
Northants were 242 for six when Wakely departed, also leg before to Gidman junior, having faced 166 balls.
The second new ball was then taken at the first opportunity and Payne capitalised by having David Murphy caught behind and David Willey bowled in the same over.
The Northants lead was just 91 at that stage, but their tail wagged energetically once more as Crook joined Middlebrook to deliver the most attacking batting of the day.
Middlebrook hit eight fours in reaching a 72-ball half-century, while Crook also punished anything loose.
By tea, the ninth-wicket pair had taken the score to 353, earning Northants a fourth batting point in the process.
Middlebrook was caught behind off Taylor's off-spin at the start of the evening session, but last man Trent Copeland then contributed 27 not out to a stand of 46 with Crook.
Will Gidman finally claimed his fourth scalp when Crook chipped a catch to Dent at midwicket, yet that came after Northants had secured maximum batting points and there was a further setback for Gloucestershire as Copeland had Klinger caught behind.