The 2005 NL Cy Young winner threw 26 pitches Wednesday several hours before the Cardinals played the Chicago White Sox. He's scheduled to throw again Friday, then a few more times next week.
"We've been getting positive feedback from all his workouts, and every step that he's taken it's always positive," manager Mike Matheny said. "But let's try not to put too much pressure on him that one thing means anything.
"We just want him to continue to get better and get him back as quick as we can."
Matheny said there was no firm timeline for Carpenter's return.
Carpenter's replacement in the rotation, rookie Lance Lynn, was tied for the National League with nine victories entering Wednesday's start. But another starter, Jaime Garcia, is on the 15-day disabled list because of a shoulder injury and could be sidelined two months.
The Cardinals are hopeful Carpenter, who was 11-9 last season and then went 4-0 in the postseason for the World Series champions, can return sometime after the All-Star break. Carpenter broke down in spring training with a nerve-related ailment that sapped strength in his throwing shoulder, after throwing 273 1-3 innings in the 2011 regular season and postseason.
The 37-year-old Carpenter said the intensity level was comparable to a session prior to the team reporting for spring training in mid-February. The right-hander said everything feels fine and is guardedly optimistic he'll pitch this season.
Carpenter said "as of right now," there's no doubt in his mind he'll be back.
"But there's always doubt," he added. "You never know. There was no doubt in my mind that I felt good coming into spring training. I'm just concerning myself with today and I was excited to get back out there and throw a little bit."