Gregory S. Mager - O

Gregory S. Mager

Listed in Best Lawyers since 2016

Gregory assists his clients with family law matters. He is recognized by judges and peers as one of Wisconsin’s premier family law attorneys. He uses his extensive skill, training, and experience to help his clients achieve successful resolutions of their divorce, paternity, custody, placement, and support matters. Gregory is a Fellow in the American Academy of Matrimonial Lawyers and a Board Certified Family Law Trial Advocate by the National Board of Trial Advocacy. He is uniquely positioned to successfully represent clients in their family law matters, including those involving complex business, financial, and child related issues.

Additional Information

Gregory Assists Clients With
  • Divorce
  • Collaborative Divorce
  • Cooperative Divorce
  • Paternity
  • Custody and Placement
  • Support
  • Post-judgment Matters
  • Mediation
  • Appellate Matters
  • Same Sex Family Law Matters



Wisconsin Supreme Court

  • Speaker, “Family Law 101” (June 2015)

Collaborative Family Law Council of Wisconsin, Inc.

  • Speaker, Second Saturday Wisconsin (February 2015)
  • Speaker, Second Saturday Wisconsin (October 2014)

Association of Family and Conciliation Courts Wisconsin/Leander Foley Matrimonial Inns of Court/Society of Family Lawyers

  • Speaker, “Utilization of Mental Health, Counseling, and Medical Records in Family Law Cases: A view from the Bench, the Bar and Healthcare Professionals” (February 2015)

American Academy of Matrimonial Lawyers—Wisconsin Chapter

  • Speaker, “May Non-Lawyers Draft QDROs?” (February 2015)
  • Speaker, “Hot Tips: Double Counting Reminders” (March 2013)

 O’Neil, Cannon, Hollman, DeJong & Laing S.C.

  • Speaker, “Asset Protection Issues in Divorce and Family Transfers” (October 2015)

  • Speaker, “Issues Relating to Recent Developments in the Legal Profession” (October 2014)

  Society of Financial Service Professionals

  • Speaker, “Financial Planning for a Second Marriage” (March 2012)


Articles/Presentations (Part 2)

American Bar Association Section of Family Law

  • Co-Producer, “Executive Compensation: Is it Income or is it Property?” (May 2006)
  • Co-Producer and Moderator, “Direct Examination of the Financial Expert: How to Make Your Point and Not Lose Your Audience” (September 2005)
  • Co-Producer and Moderator, “Hot Tips from the Experts” (August 2005)
  • Speaker, “Allocation of Dependency Exemptions in Paternity Case and Other Tax Tips” (August 2004)
  • Producer and Moderator, “Challenging the Superego: How to Prepare for a Psychologist's Testimony” (April 2004)
  • Co-Producer and Moderator, “Ethics at Trial in Spite of Your Client” (October 2003)
  • Co-Producer and Moderator, “Preparing and Presenting Domestic Violence Protective Order Cases” (May 2003)


Articles/Presentations (Part 3)

State Bar of Wisconsin Family Law Section

  • Speaker,“Tools of the Trade–A Demonstration of How to Use Different Tools That Help You Determine Financial Issues in Family Law” (August 2015)
  • Speaker, “A View from the Bench: A Panel Discussion of  Hot Topics and Tips for Beginner Family Law Practitioners” (August 2015) 
  • Speaker, “Civil Procedure, Evidence, and Pretrial Discovery” (August 2014)
  • Speaker, “Temporary Hearings—A Panel Discussion” (August 2014)
  • Speaker, “Child Related Financial Issues, Property Division Maintenance” (August 2013)
  • Speaker, “Literature Review” (August 2000)
  • Speaker, “Case Law Update” (June 1999)

Law Education Institute, Inc., National CLE Conference®, Family Law Program

  • Speaker, “The Rules of Evidence: They DO Apply In Family Law” (January 2004)
  • Speaker, “What Effective Negotiators Bring to the Table” (January 2003)
  • Speaker, “Tricks of the Trade: Low Budget Computer Applications” (January 2002)
  • Speaker, “Using a Psychologist as a Consulting Expert: Preparing Your Client for the Inevitable” (January 2001)


Marquette UniversityBA Marquette University MA
Collaborative Family Law Council of Wisconsin, Inc. State Bar of Wisconsin, Family Law SectionWisconsin Journal of Family Law (2007-2008)American Bar Association Section of Family Law CLE Committee (2005–2006)American Bar Association Section of Family Law Trial Practice and Techniques Committee (2001–2004, 2005–2006)American Bar Association Section of Family Law Trial Practice and Techniques Committee (2004–2005)American Bar Association Section of Family Law CLE Committee (2004–2005)American Bar Association Section of Family Law Bankruptcy Committee (2003–2004)Milwaukee County Circuit Court, Appointed by Hon. Diane S. Sykes (1998)

Case History

Published Appellate Decisions
  • Estate of Laubenheimer, 2013 WI 76, 350 Wis. 2d 182, 883 N.W.2d 735
  • Lyman v. Lyman, 2011 WI App 24, 331 Wis. 2d 650, 795 N.W.2d 475


Office Location

111 East Wisconsin Avenue, Suite 1400
Milwaukee, WI 53202
United States

Practice Areas

Family Law