In September 2010, Brownstein revealed her latest project was the band Wild Flag, with Janet Weiss, Mary Timony, and Rebecca Cole, formerly of The Minders; according to Brownstein, about a year earlier "I started to need music again, and so I called on my friends and we joined as a band. Chemistry cannot be manufactured or forced, so Wild Flag was not a sure thing, it was a 'maybe, a 'possibility.' But after a handful of practice sessions, spread out over a period of months, I think we all realized that we could be greater than the sum of our parts." They released a self-titled album in September 2011.
Brownstein has acted (what she calls a "mere hobby") in the short film Fan Mail, the experimental feature Group, and the Miranda July film Getting Stronger Every Day. Brownstein and Fred Armisen published several video skits as part of a comedy duo called "ThunderAnt". She also starred opposite James Mercer of The Shins in the 2010 independent film Some Days Are Better Than Others. The film had its world premiere at SXSW on March 13, 2010.