Staff

We are led by a dedicated team of professionals and volunteers who are deeply connected to the Lehigh Valley community. Some were born and raised here, others live and work in the neighborhoods we serve, and all are united by a shared commitment to walk alongside residents, build trusted relationships, and help our community thrive.

Darian Colbert

Executive Director

Darian is the founder and Executive Director of Cohesion. He has served in leadership positions in urban development work since 1999. Through these roles, he has developed partnerships with leaders in universities, the public school system, and the juvenile justice system. He has traveled the world in support of indigenous leaders working in community development in Guatemala, Haiti, the Dominican Republic, Uganda, Zambia, and South Africa.

As a passionate motivational speaker, Darian inspires individuals and communities to take action toward sustainable change. His speeches focus on leadership, resilience, and the power of collective impact, drawing from his extensive experience in community development.

In recognition of his dedication to community transformation, Darian was honored as a recipient of the 2025 Good Neighbor Award from PBS39 in the Lehigh Valley, celebrating his impact in empowering marginalized communities and fostering local leadership.

Yolanda Colbert

Director of Operations

Yolanda is a seasoned urban community organizer and advocate who focuses her efforts on the day-to-day operations of our organization. She is dedicated to optimizing the impact of existing community programs and resources, ensuring the efficient functioning of vital services at the grassroots level. Previously, she served as a program coordinator for the Weed and Seed Youth Coalition, a key component of the City’s Community and Economic Development Department. In this pivotal role, Yolanda spearheaded the coordination of federal, state, and local social services, fostering collaboration between the private sector and community initiatives. 

Amanda Helman, Ph.D.

Education Consultant

Amanda is an education training consultant, administrator, and author with 15 years of experience in the field of education. She currently teaches at Lehigh University while pursuing a Master’s Degree in Community and Trauma Counseling. She is the author of I Am Worthy, Loved, and Valued, a children’s book which inspires students to build resiliency and positive affirmation about their worth. Amanda loves reading, writing, dancing, traveling, and building connections with people from all over the world.

Board of Directors

Taressa Diaz

Board Chairperson

Taressa is an HR leader with experience as a strategic business partner, change agent and people champion, guiding leaders in people strategy, culture and engagement. She received her Masters in HR Management from Moravian College and is currently an HR Director at the Coca-Cola Company. She has a passion for social justice and providing young people with an outlet to be heard, supported, and empowered. She has served nonprofit organizations by providing creative arts classes and developing a self-esteem program for girls.

Jenna Azar

Secretary
Jenna is a graduate of Allentown School District who understands the importance of community involvement in building strong, vibrant neighborhoods and schools. She holds a Bachelor of Science in Criminal Justice and Psychology from Cedar Crest College and a Masters in Educational Leadership from Lehigh University. Jenna led the award-winning HYPE Youth Media program and has held leadership roles in higher education focused on diversity, equity, inclusion, educational access, and student success. Jenna and her husband have four sons.

Marc Rittle

Board Member

Marc is the executive director of New Bethany Ministries and lives in Bethlehem. He carries 15 years of non-profit leadership, including United Ways at Metro Chicago and Greater Lehigh Valley. A champion for housing and food security issues, he works together with local partners to solve critical social issues. Prior to working with nonprofits, Marc taught Sociology at Loyola University Chicago. He is married to Sarah Andrew, a Bethlehem area attorney, and their family enjoys hiking, bicycling, and supporting local community events and festivals.

Angela Castro

Board Member
Ms. Castro joined Acadia in 2015 and was named to the Acadia senior executive team as Chief of Staff in 2022. Prior to her current role, she was a Divisional Director of Business Development, where she worked extensively on the development of joint venture partnerships. She also served as the Director of Business Development at Acadia’s Belmont Behavioral Hospital in Philadelphia. Angela grew up on the south side of Allentown in Cumberland Gardens, and her family eventually moved to 2nd Street. She is a graduate of Dieruff High School and Cedar Crest College.

Emmanuel Lumbayi

Board Treasurer

Emmanuel joined the United States Army in 2014 and has been a Human Resources Officer since 2018. He graduated from East Stroudsburg University with a Master’s Degree in Organizational Leadership and a Bachelor’s in Business Management and Entrepreneurship. He adds tremendous value to the organization related to his experience in HR, business management, and accounting and his passion for empowering youth. He has worked as a District Manager at ADP, helping small businesses manage their finances and benefits. He is married to Ciara, and they have two children.

Tiffany Polek

Board Member
Rooted in Allentown, Tiffany Polek began her educational journey after graduating from William Allen High School. A passionate educator and single mother of two daughters, she started her career in the classroom in 2005 and went on to serve as an elementary school principal. She later led Student Services and community engagement efforts across the district, building strong partnerships between schools, families, and the broader community. Now as Executive Director of Instructional Leadership, Tiffany oversees the Inspire Learning Network and principal development. She holds degrees from Cedar Crest College and Lehigh University and is pursuing her doctorate and superintendent certification..

Bill Cummings

Board Member

Bill has served in leadership roles in urban community development work since 1994 and has his master’s degree in social and civic entrepreneurship. He founded Lemonade International in 2008 and served as its executive director for nine years. He has also served as Director of Strategic Development at Zoe Empowers, and as Chief Relationship Officer at Restore NYC. Bill leads Groundswell — a consulting and branding agency that works with nonprofits and justice-seeking organizations.

Darian Colbert

Board Member

Yolanda Colbert

Board Member