For the 18th year in a row, pairs of children will clamber into double-wide fiberglass cars for the 2015 soapbox Challenge Series Races in Issaquah Saturday.

The event will partner middle and high school volunteers with children who have special needs.

The nonprofit Life Enrichment Options will host the free event along Second Avenue Southeast from 9 a.m. to 2:30 p.m. Registration starts at 8 a.m.; participants will meet at the Issaquah Community Center at 301 Rainier Blvd. S. During an afternoon break, volunteers from the Rotary Club of Issaquah will provide lunch during the award ceremony at noon.

The free event will block off Second Avenue Southeast, from Southeast Andrews Street to Southeast Darst Street, starting at 7 a.m.

Life Enrichment Options is a community-based organization dedicated to supporting those with developmental disabilities. The statewide Challenge Races 2015 series began in Spokane June 20. It will continue in several Eastside cities, including in Sammamish Aug. 22, and ends mid-September in Snoqualmie.

“It’s just kind of one of those heartwarming events,” said Fred Nystrom, executive director of Life Enrichment Options. “It’s become, really, a nice community event.”

Nystrom expects about 30 children with special needs will participate in the race.