The strike is over workers' rights, salaries and seniority issues, said Reaz Mahmood, spokesman for the Student Support Services Staff Union, which represents 57 employees at the college.
Picket lines went up Tuesday morning and have been growing throughout the day, Mahmood said.
He said student support services employees have been trying to negotiate a contract with the college administration for the past 16 months, with little progress. The union represents mental health counselors, admissions counselors, financial aid advisers, student activity advisers and others who support students.
"A lot of our members have been underpaid for a very long time - at least since the salary freeze of 2008 - and some have been going without raises for even longer - a decade or more," Mahmood said.
"The average salary for a person in our unit is what the average worker in the state of Washington was receiving in 1992, so we really need to get up to speed on that," he added.
He said some people are refusing to cross the lines, and some professors are planning to hold class outside the classroom on the picket lines.
"We're not trying to deprive students of their educational opportunity, but we think this is actually a great educational moment for them, so they're getting an education outside the classroom in a very important way, because they're going to go out there very soon and join the labor force themselves," Mahmood said. "This is a fantastic chance for them to see how the whole process works."
Adminstrators at The Evergreen State College did not return phone calls seeking comment.