The Leaven Staff

Mark Lillis Executive Director In 2009, Mark had an opportunity to move back to his hometown of Fairfield, and help founded The Leaven, which has become an award-winning program providing after-school and summer tutoring for children living in under-developed communities in California. The Leaven, under his leadership, has become the fastest growing grassroots nonprofit in Fairfield, California, and expanded its programming to Southern California. Lillis is responsible for the strategic leadership of The Leaven's after-school tutoring centers and "Summer Success Program," volunteer recruitment and donor development. Click here for more
Renee Tadlock Operations Director Renee was a volunteer and a site director herself, before becoming the lead of our Operational team, and is thrilled to be working with each site director, helping them find solutions to challenges and making sure their great ideas are being replicated across all Leaven centers. Formerly a preschool teacher for the City of Fairfield and a para-educator for the Solano County Office of Education, she brings a huge passion for boys and girls and a heart for helping children to her work with The Leaven. Renee and her husband, Mike, serve as pastors for Real Life Church in Fairfield.
Steve Diekmann Leaven Foundation President and Financial Advisor Steve earned an MBA from the University of Chicago and worked in management consulting and financial markets in Institutional Fixed Income Sales. Steve protects our organization's fiscal integrity by ensuring that established processes, controls and safeguards are in place and assisting in growth planning and general strategy.
Michael Tadlock Church and Community Relations Director Mike Tadlock is The Leaven's Church and Community Director, working to build the church and community relationships that support all Leaven centers through valuable volunteers that are the crux of our program. In addition to his work with The Leaven, Mike serves as lead pastor at Real Life Church in Fairfield, and has built strong relationships in the communities where The Leaven operates. Mike grew up in Colorado and California, and attended Southern California College. He began his career as a youth pastor, and continues to work in partnership with his wife, Renee. The Tadlocks live in Fairfield with their two sons.
Mark Hagan Corporate Partnership Director, Regional Director, Benicia, Vallejo, Napa Mark grew up in Solano County, and has recently returned after raising his family elsewhere in California and in Arizona. His background in public relations and real estate, as well as business development makes him a natural in corporate relations. The Leaven was a program that he quickly embraced when he moved back to Solano County. “I’ve never seen a cooperative effort like The Leaven; everyone from community leaders and businesses to educators and churches pull together to impact our kids. If what you do with your money matters and you want to invest in the community, this is a great organization. It is truly changing the face of the community!”
Annika Kooistra Site Director, at Parkway Gardens Fairfield Annika Kooistra, Site Director at Parkway Gardens, returned home to Fairfield after graduating from Liberty University in Lynchburg, VA, where she worked with middle schoolers through Young Life and also where she met her husband. “A former classmate at Vacaville Christian School (the school Annika graduated from) told me about The Leaven,” Annika says, “and when I read the job description for a Site Director, I knew it was my dream job because I get to do what I love! Annika and her family attend Parkway Community Church, the church she attended as a youth.
Alex Cabillo Site Director, Grande Circle Center Alex is the Site Director at Camden Park in Vacaville, one of the Leaven centers opened in 2017. Alex is a member of Crossroads Christian Church where he has volunteered in the children’s ministry for more than a decade. Additionally, he works with Paden Knights, a program that provides positive male role models for fifth and sixth grade boys at Paden School in Vacaville, helping them develop a strong character. “I had very few positive role models as a child,” Alex recalls, which is why he is passionate about working with children. “I feel guiding children through life is how God has gifted me.” When Alex was introduced to The Leaven, he saw it was a natural fit for him.
Carly Grote Site Director, Harbor Park Carly loves being able to help children who are growing up within blocks of where she herself was raised. A graduate of Fresno State with a B.A. in Interior Design, Carly felt a call in her heart to change paths and work with children. She enrolled in Napa Valley College’s Child and Family Studies program to follow that passion. At Hillside Christian Church in Napa, Carly heard about The Leaven from Lindsay Laybourne, our Site Director at Woodland Apartments. Carly says of her role at The Leaven, “I love being part of the community. Some of our Leaven students haven’t had an opportunity to play and to explore crafts, science and other things. We give them wonderful experiences while we help them improve academically. “One boy recently said to me, ‘Thank you so much for letting us do this today!’ That’s what I wish for all my students – a chance to explore the world and see new opportunities.”
Dina Johnson Site Director, Signature at Fairfield Dina had a career in radio broadcasting that took her from Pittsburgh to Vacaville and other places in-between, but she has always had a heart for children because "Jesus loved the little children — and so do I!" she says. When she heard about The Leaven, "I had to check it out! It was an opportunity to work with children, which is my passion. I hope to see the Leaven students hunger for more knowledge — more math, more science, more English — more education so they are ready for the future. They don't have to do what others do, like gangs, drugs and crime. They can do anything through Christ." Dina is a member at Liberty Church.
Jeremiah Tadlock Site Director, Phoenix Drive Jeremiah has been volunteering with The Leaven since he was in the sixth grade, and is now site director at our Fairfield center on Phoenix Drive. Jeremiah is a graduate of Fairfield Christian High School, attending Solano Community College and Real Life Church in Fairfield. “The Leaven is a good opportunity to impact the lives of kids who may not have positive influences in their lives,” Jeremiah says. “A lot of our students struggle in school and a few can barely read at all. My goal is to help them learn to read while they grow in character and in care for one another.”
Julie Soto Site Director, Camden Parc Julie Soto, Site Director at Camden Park in Vacaville, was raised in Oakland but later moved to Vacaville with her children. Following a 30-year career in healthcare including 10 years with University of California San Francisco, Julie sought an opportunity to volunteer. "Jeremiah 25:11 says, 'I know the plans I have for you,'" Julie says, "and I knew God would give me a path." She learned about The Leaven at church (Real Life Church in Fairfield) and was encouraged to apply to join the Leaven team. "Kids are so eager to learn, and they need to be shown that they have value and that life is so much more than material things," Julie says. "I know God placed me at Camden Park to share the love of God with the students." Julie is a mother of five daughters and "just can't wait" to get to the Leaven center every day to help the children learn and grow.
Kayla Cordell Bio coming soon.
Krista Edgens Site Director, Bella Krista Edgens, our Site Director at Bella Park in Rialto, attended school not far from where the center is located. After being in the foster care system, Krista was adopted at age four and later attended Bloomington Christian School, just south of Rialto. A good friend introduced her to The Leaven and she began as an intern in a Southern California center before taking over as Site Director at Bella Park. “I see in our Leaven kids some of the same emotional issues that I faced,” Krista notes. “I want them to see in me someone who understands, who will listen to them, and who can perhaps give them more attention than their parents who are working so hard simply to provide for their needs.” Krista completed her A.A. degree in Social and Behavioral Sciences from Valley College in San Bernardino. She attends Calvary Chapel in Rialto and excited to be modeling Christ’s love to her Leaven students. “The Bible says in Proverbs 21:31 that ‘The horse is made ready for the day of battle, but victory rests with the Lord.’ That reminds me that no matter how prepared I am, I won’t succeed without God.”
Lindsay Laybourne Site Director, Woodland Lindsay, Site Director at the Woodland Center, is “back home,” having grown up in a neighborhood near the apartments. It is a joy for her to be working at this site because “I’m working in the community I grew up in, and I am giving back to the kids there,” she says. “When I heard about The Leaven in Napa, I was overwhelmed because I know firsthand how much these children need this program. Despite living in a town that is world-renowned, the children from the Woodland Apartments don’t know the kinds of opportunities that are available beyond their neighborhood. The Leaven helps the students expand their world view and see what is possible for them.” Lindsay is a graduate of the California State University in Sacramento where she received her B.A. in History.
Maria Dennis Site Director, Carolina Heights Maria Dennis, is a native of Portugal. Her path took her to Kenya for Y-WAM’s Discipleship Training School, where she met Tristan, a fellow student and a Northern Californian. They were married in 2017 and today make their home in Vallejo. Maria’s dream is that The Leaven students will become “very confident children who have learned what their strengths and weaknesses are, and can independently pursue their goals. I want them to dream bigger than they are dreaming today.” Maria attends Bridgeway Church in Vallejo.
Mary Brown Site Director, Marina Marina Vista Mrs. Mary Brown comes to The Leaven with a varied background that includes a career in public relations, Corrections, founding Savannah’s Safe House Publishing, owning Optimal Body Fitness, and authoring a book series for children called “Happy the Hitchhiking Praying Mantis” and “The Little Man in the Big Suit.”Mary’s vision for Leaven students at Marina Vista is that they will discover God's purpose for their lives and apply their talents to help others. Mary attends Church on the Hill in Vallejo.
Mason Tadlock Regional Director, Fairfield, Suisun and Vacaville Mason graduated from Fairfield Christian School and is currently studying at Liberty University. He is thrilled to be able to both help the next generation improve their academics and learn about Christ-like character by seeing His love in action at The Leaven.
Naima Hester Village Apartments Bio coming soon.
Natalie Rios Site Director, Alamo Gardens Natalie is a homeschool mother of six children who has also worked as a math tutor, Natalie knows that “not every child gets the opportunity for intentional one-on-one time with an adult, but through The Leaven, we can change that as we help families feel a sense of belonging. We want them to know that they aren't just living in a community; they are an integral part of that community.”
Portia Kenny Site Director, Burgess Pointe Portia has “Leaven roots” as her father was previously on our staff. “I have volunteered with The Leaven in the past, so when I came back to the area, my dad suggested I contact them to see if there was an opening.” Portia was thrilled to be invited to serve in the same center where her father had previously worked. “My goal is to help build the confidence level of the students,” Portia says. “A lot of them feel like they can’t achieve something; they can’t do it. As a result, they give up before they try. My message to them is, ‘You do have the tools and you are capable of doing well in school.’” Portia attends The Hill Vallejo. She’s excited to be part of The Leaven!
Sandie Lawler Site Director, The Groves Sandie grew up in a low-income household without a stable father figure in her life. She attended 14 schools in 12 years, ending up on Long Island, New York. There she met the man she would marry, and they have been serving the Lord together for nearly 40 years. Sandie’s goal is to stimulate the children to develop specific character qualities so they can grow up to be good citizens. She’s also passionate about reading: “I’ve found that children who have a harder time with reading often don’t have the joy of reading. I want to get them to enjoy reading for life!”
Stephanie Yamato Site Director, at Dana Drive Fairfield Stephanie Yamato moved from Ventura County to Solano County when she was a teenager. She has been very involved in the church community as an adult, serving in nursery, children’s church, youth and pastoral roles. Stephanie, who is a licensed childcare provider and has studied early childhood education, was drawn to The Leaven because it “combines everything I love – God, children and helping people. The Leaven mirrors my life!” Stephanie is the mother of two teenage daughters and attends Solid Rock Church of God in Vacaville.
Teesha Jones Site Director, Ontario (Southern California) Teesha has three boys ranging in age from teenagers to the early 20s, and knows the importance of reaching children before they get to the critical years in junior high school and high school. She is a lifelong resident of Southern California and is studying to be a nurse as well as serving in our operations.
Tristen Dennis Sereno Village Bio coming soon.