Lululemon Athletica Inc. employees will vote this month on unionizing a store in Washington, D.C., testing the strength of an organizing wave that’s been sweeping through previously union-free U.S. retail firms.

The U.S. National Labor Relations Board has approved an agreement between the company and the new labor group organizing the location, the Association of Concerted Educators, to hold an election on Aug. 26 and 27. The planned vote follows a series of landmark labor wins in elections at companies including Starbucks Corp., Amazon.com Inc., Apple Inc., and Trader Joe’s.

The organizing group, whose name is drawn from Lululemon’s practice of calling its retail staff members “educators,” petitioned last month to represent a crew of about 33 workers at the D.C. store. Lululemon said at that time that it would “respect the process” and welcomed “continued conversations” with staff.

In a statement today, ACE said it’s looking forward to the vote and expects to win support. “We expect Lululemon to come to the bargaining table with our core values in mind ready to bargain our first contract,” said the group, an independent organization led by Lululemon staff.

Lululemon shares fell 3.3% as of 11:47 a.m. in New York and have declined about 22% so far this year.