Jeff Zillgitt

USA TODAY Sports

Lauren Holtkamp had just finished school and a basketball career at Division II Drury University in Springfield, Mo., a decade ago and contemplated what to do before pursuing a master's degree in divinity.

A former teammate's dad invited Holtkamp to a local referees meeting, and in 2004, she reffed her first game — a middle-school contest in Springfield.

Ten years later, Holtkamp, 33, is now a staff official for the NBA, becoming the third woman to ref NBA games full-time, joining Dee Kantner (now the WNBA's supervisor of officials) and Violet Palmer (a current NBA referee).

"Part of the satisfaction of earning this opportunity has to do with the fact that I've been able to stay committed to the work and put the work first and trust the system and that's what matters," Holtkamp told USA TODAY Sports. "It doesn't matter who is doing the work as long as the work is high quality. There is a great deal of satisfaction in that."

Holtkamp is one of three officials to make the jump from the NBA Development League to the top league this season. Dedric Taylor and Justin Van Duyne also joined the 63-person roster.

She said she appreciates what Kantner and Palmer have accomplished. "There is a kinship and certainly a sense of support and collegiality."

But Holtkamp is emphatic that she is a referee who happens to be a woman.

"I would say really from day one when I got hired into the D-League I've been treated as a referee as far as my performance," she said. "It's been about my performance and the quality of work."

Holtkamp made it to the NBA's full-time staff the same way the past 40 additions have made it since 2001: through the D-League's training program. It is a comprehensive instructional program that includes three levels (grassroots, intermediate and elite) before an official refs a D-League game.

NBA associate vice president of referee development George Toliver, a former NBA official, runs it. Toliver and his staff identify potential D-League refs and invites them to the program. Advancing from one level to the next is based on several factors (fitness, court presence, command of situations), including a high rate of making accurate calls.

"We bring them to our basic camp," Toliver said. "We teach. We have instruction and classroom sessions. We cover the basics and what we look for in a basketball referee. Then we watch them work."

Toliver saw Holtkamp's work and invited her to the program. She began calling D-League games in 2008 and has been working D-League, WNBA and college games since.

"Within four years of putting on a whistle, I was starting my experience in the D-League," Holtkamp said. "At the time, I wasn't sure I was ready in terms of skill and I wasn't. Looking back, we started from ground zero. That's the genius of George's development program. He will teach us good habits from the beginning so we maximize our development in a shorter amount of time."

The average time from D-League to NBA is five or six years, Toliver said, and of course, not all D-League officials make it to the NBA. Some are eventually dismissed from the program.

The documentary Summer Dreams, shot in 2013, focused on rookies trying to make it to the NBA, a D-League coach and Holtkamp. It was Holtkamp's fifth season in the program, and in the documentary she said she heard a voice inside her head, "You're not good enough."

But the 2013-14 season gave her a ton of confidence. She reffed six NBA games as a non-staff official, and going into the 2014 Summer League she said she felt prepared.

"I felt I was really on the cusp of earning this opportunity. … I felt really healthy physically, mentally, emotionally and I felt confident in the work and trusted that the work would be enough," Holtkamp said.

In early August she was in San Antonio for a WNBA game and received a call from Mike Bantom, the NBA's executive vice president of referee operations. It was a brief call, Holtkamp said, but he invited her to join the NBA's officiating staff.

"We don't bring referees from the D-League to the NBA to learn how to be an NBA referee," Toliver said. "We train them to be ready and they don't get a recommendation if they're not ready to walk in and know how to referee at that level every single night."

Earlier in life, Holtkamp envisioned a career as a chaplain working in a hospital, women's prison or mental health center. But officiating, she said, is her calling right now, and she takes a holistic approach to the work.

"In order to be in the space to make the best decisions night in, night out, it really demands 100% effort physically, mentally, emotionally," she said. "I am able to participate in a career where I can bring the fullness of who I am to the work."