WILLIAMSBURG, Virginia, May 2, 2013 (AFP) - "Today, I played very good, so my putting helped me a lot," said Ariya, whose nine birdies more than countered the only blemish on her card, a double-bogey five at the par-three 17th.
"I made a lot of putts, but today I still missed on my driver and long irons."
The 17-year-old, who is playing on a sponsor's exemption, had a two-shot lead over US veteran Cristie Kerr.
It was a further stroke back to South Korea's Ryu So-Yeon and Dewi Claire Schreefel of the Netherlands on 67.
World number one Park In-Bee and number two Stacy Lewis were among a group of 14 players sharing fourth place on three-under 68.
Ariya, of Bangkok, captured her first professional title in March, when she claimed a three-shot win at the Lalla Meryem Cup in Morocco on the Ladies European Tour.
She was fast out of the gate on Thursday, with birdies at the first, second and third holes. She reeled off three more birdies from the fifth to make the turn at six-under.
The player was eight-under through 14 before finding trouble at 17, where she missed the green and needed two chips to get on the putting surfaces.
She bounced back with a birdie at 18.
"On 17, I just missed to the left and just had a bad third shot and second shot," said Ariya, who has finished in the top five in all three LPGA events she has competed in this season.
"It did not make me not confident because I knew 18 is not a long par-four, so I could make a birdie on that hole."
Kerr's round included six birdies and just one bogey. She finished in style, with birdie at 17 and 18.
"Momentum's always the thing that you want to try and have," she said. "Tomorrow's a new day, though, new feel, how you're feeling. You try and carry over the play from today into tomorrow as best you can."
Ryu teed off on 10 and had four birdies in her first nine holes. She closed with nine pars.
Defending champion Shin Jiyai of South Korea, who set the course record of 62 en route to victory last year, carded a one-under par 70 and was tied for 39th.
Leading first-round scores on Thursday in the LPGA Kingsmill Championship (par-71)
65 - Ariya Jutanugarn (THA)
66 - Cristie Kerr
67 - Dewi Claire Schreefel (NED), Ryu So-Yeon (KOR)
68 - Katie Burnett, Ai Miyazato (JPN), Stacy Lewis, Jane Park, Angela Stanford, Sandra Gal (GER), Karen Stupples (ENG), Mo Martin, Suzann Pettersen (NOR), Caroline Hedwall (SWE), Azahara Munoz (ESP), Park In-Bee (KOR), Lee Jee-Young (KOR), Park Hee-Young (KOR)
69 - Stacy Prammanasudh, Sarah Kemp (AUS), Jennifer Rosales (PHI), Christel Boeljon (NED), Alison Walshe, Tseng Ya-ni (TPE), Choi Na-Yeon (KOR), Amy Yang (KOR), Juli Inkster, Meena Lee (KOR), Thidapa Suwannapura (THA), Lee Il-Hee (KOR), Mina Harigae, Lindsey Wright (AUS), Mindy Kim, Lisa McCloskey, Paola Moreno (COL), Paula Creamer, Lorie Kane (CAN), Feng Shanshan (CHN)