Tony Palladino took 6-29 to put Derbyshire in control as 21 wickets fell on Day Two of the Specsavers County Championship match at The 3aaa County Ground.
Palladino claimed his 14th five-wicket haul for the county as the hosts produced a dominant bowling display to dismiss Glamorgan for just 121 shortly after lunch.
Alex Hughes hit a well-made 57 – only the second half-century of the match – in reply, while Harvey Hosein scored 31 as Derbyshire posted 171 in their second innings, setting Glamorgan 302 to win.
Palladino then returned to remove Stephen Cook (5) before stumps to leave the visitors 16-1.
Four-day cricket is back! Derbyshire host three Specsavers County Championship matches in August and September. Buy your tickets in advance and save.