The legendary rock star penned a letter to Illinois lawmakers asking them to pass the amendment.
"Please vote yes on the Equal Rights Amendment. I have three daughters who are US Citizens and they should all deserve rights under the Constitution of the United States."
Jagger's daughter Elizabeth shared his letter on Instagram.
The text of the Equal Rights Amendment states that, "Equality of rights under the law shall not be denied or abridged by the United States or by any State on account of sex."
The Equal Rights Amendment first went before state legislatures in 1972. Since then, 36 states have passed the amendment, and Illinois would be the 37th if ratified by the state legislature.
In 2017, Nevada became the first state to ratify the amendment since 1977, doing so decades after the deadline for ratification.