The index registered a 50.9 percent rating for overall business activity in manufacturing, which is nearly 2 percentage points better than in May, according to Arizona-based ISM.
Optimism often shares a couch with caution.
"June is a balanced report, and one which reflects slow growth with slow improvements. Nothing dramatic," Bradley J. Holcomb, chairman of ISM's Manufacturing Business Survey Committee, said in an email.
In part, that's because employment measurements in the index have slowed by 1.4 percentage points from May, he said. However, the hiring slowdown could be a temporary thing, he said.
But there's also the new orders index, which showed manufacturers saw a more than 3 percent increase in new business from the previous month, according to ISM.
There's some nuance in the numbers, Holcomb said.
"So for now, it is a month-to-month situation, dependent upon continuing consumer confidence and global economic stability and growth," he said. "Manufacturing is well positioned for growth, but those factors just mentioned — manifested in new orders — will rule the day."