About Tidemark
Tidemark partners with mission-driven institutions, foundations, and leaders to design philanthropic impact that endures. Grounded in strategy and narrative clarity, we help organizations align purpose with performance, translating aspiration into measurable impact.
Philanthropy, at its best, is both vision and structure: the meeting point of generosity and discipline. We work with change-makers who believe in doing good with precision, where legacy is an architecture.
Why Tidemark
The word tidemark describes the visible line left when the tide has reached its highest point. We exist to help institutions reach, and define, theirs.
Tidemark was founded on the belief that precision and courage, grounded in purpose, can transform institutions.
We partner with schools, foundations, and mission-driven organizations to design advancement strategies rooted in trust and long-term impact. Our work helps leaders move through complexity and navigate change with steadiness and vision.
About the Founder
Erika McMahon is a nationally recognized advancement strategist and advisor whose work work supports mission-driven institutions across education and the nonprofit sector. Her career has been dedicated to helping organizations raise transformational support while building enduring cultures of philanthropy, trust, and leadership alignment.
Over the past two decades, she has led schools, universities, and foundations through record-setting campaigns and periods of significant organizational change, partnering with boards, senior leaders, and donors to align ambition with institutional readiness and long-term impact.
Before founding Tidemark, Erika served as Chief Advancement Officer at The Winsor School and Notre Dame Academy, and held senior advancement leadership roles at Simmons University, guiding advancement strategies across two $100M campaigns and overseeing comprehensive fundraising, engagement, and communications programs.
Her expertise in women’s philanthropy and leadership alignment informs a distinctive, values-based approach to institutional advancement; where trust, transparency, and disciplined strategy drive results.
A published writer and speaker, Erika is the author of The Tide Report, a series of essays exploring leadership, culture, and philanthropy for senior leaders, boards, and advancement executives. Her writing examines how institutions navigate trust and growth, with particular interest in patterns surrounding the rising influence of women in leadership. Her essays have appeared in Boston.com, and WBUR Cognoscenti, and she has presented at national conferences including CASE-NAIS, NEDRA, and more.
Erika brings both strategic precision and deep relational insight to her advisory work; partnering with institutions as an integrated member of their leadership teams to build strategy, momentum, and lasting impact.
