After showing slower growth for two consecutive months, the Purchasing Managers Index for May came to 53.7, up from April's 53.5 reading.
With numbers above 50 indicating growth, May marked the 29th consecutive month of growth in the U.S. service sector.
The index for new orders in May rose from 53.5 to 55.6. The employment index, however, slowed from 54.2 to a near break-even month at 50.8.
Both the new orders and the production indexes have remained positive for 34 consecutive months, the production index rising from 54.6 to 55.6. The employment index, while slipping close to 50, has been positive for 5 consecutive months.
In the month, 13 of 18 service industries tracked in the report showed growth, led by information services, transportation and warehousing, accommodation and food services and company management.
Arts, entertainment and recreation, healthcare and social assistance, and mining reported business contraction in the month.