Tsongas is pro-choice and received a 100% approval rating from Planned Parenthood in 2008. A supporter of LGBT rights, she cosponsored the Respect for Marriage Act to repeal the Defense of Marriage Act; and voted for the Don't Ask, Don't Tell Repeal Act of 2010, which allows gays and lesbians to serve openly in the United States Armed Forces.
Tsongas is a strong advocate for reproductive rights and has received unwavering support from Planned Parenthood, earning a perfect score in 2008. She is also an ally to the LGBTQ+ community, having co-sponsored legislation to repeal discriminatory laws and voted in favor of allowing openly gay and lesbian service members.