CARLSBAD, March 29, 2014 (AFP) - Carter had 11 birdies -- including seven in a row from the 10th -- and three bogeys as she built a 10-under par total of 134.
Seeking a first win on the LPGA Tour, she had a two-stroke lead over fellow Americans Stacy Lewis and Cristie Kerr. Lewis, the world number three, carded a 66 and Kerr a 68.
American Lizette Salas produced her second straight bogey-free round and was a further stroke back after a 68 for 137.
Although she closed with two bogeys, it is the first time in her four-year LPGA Tour career that Carter has led after any round.
"I just have to take it for what it is and hope that I'm here talking to you a little more often," she said.
"I have no reason to be uptight or anything because this is my first time. I'm OK with that. I'm OK with feeling like no matter what happens -- obviously I want to win -- it can't be a bad thing for me."
Lewis said seeing Carter go so low at Aviara Golf Club was surprising given the difficulty of the course.
"It's very impressive," Lewis said. "It's a hard golf course. You can make a double pretty quick, so it's a hard golf course."
Kerr said an eagle on the par-four first hole -- her 10th of the day -- jump-started her round.
"I shot even on the front and kind of left a couple out there," she said. "And that was just a great shot. Couldn't see it go in, unfortunately, but it was a great seven-iron, perfect club, and I just said get close, and it went in. So it was cool."
Carter hadn't teed it up in an LPGA event since the Australian Women's Open more than a month ago.
The 27-year-old said three starts in the lower-rung Symetra Tour had kept her sharp.
"I always play better when I'm playing constantly... no matter what tour it is," she said.
Leading second-round scores on Friday in the US LPGA Kia Classic (par 72, USA unless noted):
134 - Dori Carter 70-64
136 - Stacy Lewis 70-66, Cristie Kerr 68-68
137 - Lizette Salas 69-68
138 - Tiffany Joh 69-69, Mariajo Uribe (COL) 67-71
139 - Chella Choi (KOR) 74-65, Lexi Thompson 69-70, Feng Shanshan (CHN) 68-71, Paula Creamer 67-72
140 - Pak Se-Ri (KOR) 70-70, Park In-Bee (KOR) 69-71, Julieta Granada (PAR) 70-70, Ashleigh Simon 71-69 (RSA)
141 - Anna Nordqvist (SWE) 73-68, Jenny Suh 72-69, Ai Miyazato (JPN) 70-71, Ryu So-Yeon (KOR) 70-71, Azahara Munoz (ESP) 69-72, Lee Mi-Hyang (KOR) 68-73, Ayako Uehara (JPN) 70-71
142 - Lydia Ko (NZL) 74-68, Jenny Shin (KOR) 73-69, Oh Ji-Young (KOR) 72-70, Tseng Ya-ni (TPE) 71-71