A Tradition of Excellence

Sinclair Advisory Group LLC (SAG) provides high-quality strategic planning, leadership training, executive coaching, and specialized consulting services for both public and private sector clients. 


SAG was founded in 2006 by Stan Sinclair, a retired federal executive with an extensive background developing and leading large organizations.  His partner, Seth Sinclair, a credentialed Leadership Coach and certified Project Management Professional, helped him co-found the company and now serves as the Chief Operating Officer.


Our motto is "Excellence from Experience" because our team of consultants, trainers, and coaches is comprised of senior-level professionals and recognized industry experts who bring substantial career experience across a wide range of functional areas. 

Seth Sinclair, Member & Co-Founder

Seth Sinclair is an experienced senior leader, management professional, and entrepreneur with expertise in all aspects of business planning, development, operations, and delivery.

Within his twenty years of experience, Seth has:

  • Co-founded and operated two successful companies (, starting both from scratch, achieving growth, and sustaining successful operations.
  • Developed business across a diverse range of private and public sector clients, built long-term relationships with client leaders and executives and led projects resulting in significantly improved organizational performance, savings, and operations.
  • Personally authored a proprietary Business Planning methodology designed to and help companies link strategy, operations, and budgeting into one process and co-designed a proprietary Software as a Service (SaaS) Business Planning solution (4Cast) currently in use by 3500+ users.
  • As a professionally trained Project Management Professional (PMP), utilized extensive project management skills to successfully deliver hundreds of projects, to include all aspects of project initiation, planning, scheduling, delivery, monitoring, and closing.
  • Developed expertise, training materials, and articles across a variety of critical topics related to organizational development and business improvement, including concepts related to planning, team building, process improvement, conflict resolution, negotiation, and supervisory skills.
  • Worked with a regional firm in the DC area to establish a Federal practice and with an international firm as a manager for large scale technology integration projects.

Seth is recognized for his ability to facilitate collaborative discussion, offer innovative ideas, identify strategic themes, and lead teams in clarifying and solving critical organizational issues. 

Seth was professionally trained in Project Management and Leadership Coaching.  He has taught hundreds of classes on topics related to planning, leadership, problem-solving, and communication.  In addition to his day-to-day professional responsibilities, he has been a member of a Vistage CEO Group, held a professional credential in Leadership Coaching, has served as Adjunct Faculty for the George Mason and Rutgers University “Leadership Coaching for Organizational Performance” program, and founded a local “Loudoun County Business Mastermind” peer group.

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