Republican candidate Howard Rissell, 67, also said he was running to maintain good government.
"I'm pretty well satisfied with the way things are running," he said. ''That's the direction I want to go."
Rissell, who is retired from Lukens Steel, has served eight years as president of the Thorndale Fire Company.
The third candidate, Democrat Frank Laurento, is making his second run for commissioner, having made an unsuccessful bid four years ago.
"I've been hearing a lot of faint cries over the years for help," Laurento said. "There's a lot of different things that bug me. They're always passing laws to ban this and ban that. But they're not doing anything for the kids."
Laurento, 36, cited the board's recent decision to ban skateboards on township streets. Youngsters now may ride skateboards only on private property and only with written permission.
Laurento said that if the commission were going to stop children from using township sidewalks and parking lots, it should provide an alternative place for riding skateboards.
Laurento, who works at Pepperidge Farm in Downingtown, said he has been campaigning door-to-door to overcome a disadvantage in party registration. Republicans outnumber Democrats by about 2 to 1 in Caln Township.
He is hoping people will vote for the candidate, not the party, he said. If they do, "I think I have a darned good chance of winning."
The three candidates are seeking to replace Commissioners Al Hanscom and Alan Jarvis, both Republicans, who are not seeking re-election.