David H. Diesslin founded Diesslin Group, Inc. in 1980 with a bold, principled vision: to provide objective, client-first financial advice in an industry largely driven by commissions and product sales. Long before “fiduciary” became a widely known term, David championed a transparent, fee-only model that prioritized the client’s best interest above all else.
At a time when most financial professionals earned income through product commissions, David was among the first to reject that structure—helping lay the groundwork for a fiduciary movement that reshaped the profession. His early involvement with the National Association of Personal Financial Advisors (NAPFA), where he later served as president, positioned him as a central figure in advancing the fee-only standard nationwide.
Throughout his 42-year career, David earned widespread recognition. He was featured in Money, Worth, Medical Economics, and Fort Worth Inc. magazines, and named among “America’s Top Financial Planners” by the Consumers’ Research Council of America. His influence extended to shaping professional ethics and policy through leadership roles as Chairman of the Board of Governors for the Certified Financial Planner Board of Standards and as a strong voice for professional excellence and education.
David’s impact wasn’t limited to his firm or his clients. He mentored fellow advisors, championed ethical training for future financial planners, and contributed to the professionalization of the financial planning field both in the U.S. and abroad. He believed deeply in the power of education and diversity, establishing the Deena Jo Heide Diesslin Foundation to support underrepresented groups pursuing careers in financial planning.
His leadership was grounded in service—rooted in the belief that financial advisors are stewards of their clients’ futures. David’s personal motto, “Helping people help people,” wasn’t just aspirational; it guided every client conversation, policy contribution, and mentoring moment.
Today, Diesslin Group proudly carries his legacy forward. We continue to operate as an independent, fee-only fiduciary firm—offering the same principled advice and unwavering commitment to our clients that David modeled for decades. His vision continues to shape the profession and inspire future generations of financial advisors to uphold the highest ethical and professional standards.