Small companies added 71,000 jobs while moderate-sized firms gained 74,000 and large firms 32,000, ADP said in a monthly report delayed for a day by the Labor Day holiday.
ADP said 198,000 jobs were added to the economy in July, a revision of an earlier report that put the figure at 199,000.
The firm said the manufacturing sector added 5,000 jobs for the second consecutive month. Financial firms gained 1,000 jobs after adding 4,000 in July. Construction added 4,000, a sharp drop from the 22,000 gained in July.
Among all categories, professional business services gained the most jobs, adding 50,000 positions after gaining 49,000 in July.
The month's gain of 176,000 is just ahead of the average gain of 174,600 jobs per month over the past 12 months.