The "Superstore" actress, 36, announced on Instagram this weekend that she and her husband, Ryan Piers Williams, welcomed baby No. 2 last week.
"Lucia Marisol Williams arrived on May 4th to give me my Mother's Day hugs and kisses herself," America captioned a photo of her hand clasping her new daughter's tiny fingers.
"Mama, Dada & Big Brother are over the moon to welcome her bright light to our family," she added, referencing the couple's 1-year-old son Sebastian.
The rest of the post, including a set of videos, was dedicated to highlighting the work America's been doing with the Yes We Can Foundation, which bills itself as the "first fully bilingual school program for migrant children at the U.S.-Mexico border."
"Quarantine may have canceled her Baby Shower," America continued, "but it didn't stop us from collecting and delivering essential supplies to #YesWeCanMobileSchools – spaces for moms and children at the border to learn, play, and stay safe through these hard times."
The actress went on to appeal to friends who may be planning to send a gift to Lucia to consider making a donation to the Yes We Can Foundation in her name instead. She noted that it would also be a great time to donate on behalf of "the moms you love," then thanked her friend Eva Longoria for her help in organizing the plan to make donations in Lucia's name.
"I feel like motherhood makes me feel all the more powerful and capable and amazing," America told "Entertainment Tonight" last year, just a few months after welcoming Sebastian.
In the same interview, she called her "girlfriends who are also mothers," like Eva, her "saving grace." Eva's said the same of America, describing their friendship as "inspiring."
America and her actor-director husband tied the knot in 2011.