James Taylor led a steady batting display from Nottinghamshire's top order as they moved ahead of Division One rivals Derbyshire by the end of day two.
England batsman Taylor was unbeaten on 67 as the visitors reached the close at Derby on 325-5 in their first innings, meaning they lead their opponents by 69.
Derbyshire did not help their cause by dropping two catches but did keep themselves in the contest by taking the wickets of Samit Patel (48) and Riki Wessels in the final session.
Resuming in the morning on 28 without loss, Nottinghamshire openers Ed Cowan and Alex Hales made serene progress as both batsmen registered half-centuries.
Cowan looked on course for a big score until, when on 59, he pulled a long hop from spinner David Wright to mid-wicket, allowing substitute fielder Gregory Cork - son of former England international Dominic - to take the catch.
Hales had found batting a little tougher in contrast, at one stage going 37 balls without scoring. He did pick up the pace to make 56 from 153 deliveries.
Having been dropped on 21, Michael Lumb contributed 44 before becoming the third wicket to fall, allowing Patel to come to the crease and share in a fourth-wicket stand of 89 with Taylor.
The England all-rounder saw his knock come to a rather unfortunate end, though, when he skidded on his back looking to take a single, meaning he was stranded in mid-pitch when Billy Godleman's return landed in wicketkeeper Tom Poynton's gloves.
Wessels chased a wide one from Ross Whiteley but skipper Chris Read played aggressively to score an unbeaten 27 from 34 balls to keep his team on top at the halfway stage of the contest.