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Intensive Russian Language Institute, Indiana University
B.S. in Political Science and Russian Studies, University of Michigan
J.D., Suffolk University Law School
Masters in Public Administration, Harvard University, John F. Kennedy School of Government

Katherine Triantafillou, Esq. is an innovative lawyer, mediator and teacher with over 40 years of litigation practice in Boston and Martha’s Vineyard. She began her legal career as a sole practitioner in Boston in 1975 specializing in lesbian and gay legal matters as the founder of the first openly LGBT law firm and lawyer in Massachusetts. Soon thereafter, as counsel to Transition House, she became a specialist in battered women’s issues and co-wrote the Abuse Prevention Act (Chapter 209A), one of the first in the nation to address domestic violence and a model for other states.

Katherine’s early career concentrated on clients whose lives were seriously impacted by deficiencies in the law as it pertained to LGBT clients: losing custody of their children, fired from their jobs, prosecuted for crimes arbitrarily, victimized by hate crimes or hoping to protect their families with wills, contracts or real estate. Her general practice took her to courts throughout the Commonwealth as well as the Appellate and Supreme Judicial Court. In 1991, she was the founding partner of Triantafillou & Guérin, PC, a boutique law firm in Cambridge, MA.

In 1993, Katherine won a precedent setting case in the Supreme Judicial Court that allowed co-parent adoption and paved the way for same sex marriage. In 1994, she was featured in Boston Magazine as one of the city’s top lawyers and recognized in Feminists Who Have Changed America.

Previously, Katherine taught Family Law as an adjunct professor at Suffolk University Law School and Sexual Orientation Law at Northeastern University Law School. She also developed and taught family law paralegal training programs at Boston University, the University of Massachusetts and Transition House. As a member of Mediators Beyond Borders, she trained mediators in Greece, the Czech Republic and Cambodia. She has also worked internationally on civil society projects in Kosovo, Bosnia and Azerbaijan.

Katherine served three terms as a City Councilor in Cambridge and five years as Chair of the Town of West Tisbury Finance Committee. She graduated from the Harvard Kennedy School of Government (MPA 1999), Suffolk Law School (JD 1975) and the University of Michigan (BS with distinction 1972). She is a frequent lecturer at continuing education seminars and Editor of “Representing Non-Traditional Families” (MCLE 2000,2002) as well as co-author of “Cultural and Diversity Issues in Mediation,” a chapter in the MCLE practice guide for mediators and The Massachusetts General Hospital Textbook on Diversity and Cultural Sensitivity in Mental Health (May 2016, 2019).

In 2011, Katherine became an affiliate of Boston Law Collective, LLC where she spearheaded the firm’s divorce litigation section handling complex high value family separations, co-parent adoptions, guardianships and surrogacy issues.

The current focus of Katherine’s practice is co-parent adoption, divorce second opinions, guardianships, end of life planning and organization. Katherine is available for court appointments as a neutral personal representative or conservator in contested or uncontested matters and continues her work as a highly regarded mediator for family and estate/probate, business matters, as well as international training/facilitation. Katherine is a frequent volunteer at Massachusetts Continuing Legal Education programs on Family Law Mediation where she leads sessions on Diversity and Inclusion providing lawyer/mediators with safe spaces to examine relevant issues of racism, homophobia and other forms of bias.

Professional Affiliations & Community Involvement

Massachusetts Bar Association
Family Law Section Council (2007-2010)
Chair, Individual Rights and Responsibilities Section (1990-1992)
Gender Bias Column Committee, Lawyers Weekly (1991)
President’s Committee on Alternative Dispute Resolution (1984-1986)
Bench/Bar Subcommittee on Probate Court Procedures, Chair (1988)
Boston Bar Association
Fee Dispute Committee (1991-1992)
Family Law Section, former member
Member, Case-Flow Management Subcommittee (1987)
Organizer, Panel of Assistant Registers (1987)
Chair, Court Facilities Subcommittee (1988)
Massachusetts Law Reform Institute, Family Law Task Force, former member
Advisory Board, Suffolk University Law School Continuing Legal Education, former member
Fellow, Massachusetts Bar Foundation
American Bar Association
Founder, former Co-Chair, current member National Lesbian and Gay Law Association; Massachusetts Lesbian and Gay Bar Association
Kennedy School of Government New England Alumni Association (KSGNE)
Member, Executive Committee (2002-2004)
Principal Drafter, Association By-Laws
Clerk/Secretary (2004)
Democratic State Committee (2000-2004)
Board of Directors, MassEquality (2005-2010)
Finance Committee (2005-2008)
Vice-President (2007-2008)
Member, Town of West Tisbury Finance Committee (2011-present)
Chair, Town of West Tisbury Finance Committee (2012-2018)



  • “Domestic Violence and CyberShelter,” World Conference on Family Violence, 2000, Cyprus
  • “Domestic Violence Free Zone: Framework for Municipal Efforts to Combat Violence Against Women,” World Conference on Family Violence, 1999, Singapore

  • “Azerbaijan – Baseline Assessment of Municipalities,” IFES, 2002, Baku, Azerbaijan
  • David Hoffman & Katherine Triantafillou, Cultural and Diversity Issues in Mediation and Negotiation, in The Massachusetts General Hospital Textbook on Diversity and Cultural Sensitivity in Mental Health, Current Clinical Psychiatry (Ranna Parekh, ed., 2014)
  • David Hoffman & Katherine Triantafillou, Cultural and Diversity Issues in Mediation, in Mediation: A Practice Guide For Mediators, Lawyers and Other Professionals (David Hoffman, ed. 2013)
  • Katherine Triantafillou, Same Sex Conflicts: A Primer for Mediators, 12 Fam. Med. Q. 20 ( Spring 2013)
  • Katherine Triantafillou, ed., Representing Non-Traditional Families, (1st & 2nd editions 2000, 2006)
  • Katherine Triantafillou, Sample Pleadings: Abuse Prevention Act, in Charles Kindregan and Monroe Inker, Family Law and Practice (1st Edition, 1990)
  • Katherine Triantafillou, Property & Custody Rights of Unmarried Couples (April, 1989)
  • Katherine Triantafillou, Update on Case Summaries: Care and Protection, in Guardianship and Termination of Parental Rights Proceedings (1989)
  • Katherine Triantafillou, Massachusetts: New Legislation to Help Battered Women, 27 The Judges’ Journal, No. 3 Summer (1988)
  • Katherine Triantafillou, ed., Massachusetts Police Institute Training Manual on the Abuse Prevention Act (1979)
  • Katherine Triantafillou, Do Your Own No Fault Divorce (1979)
  • Katherine Triantafillou, et. al., Legal Rights of Battered Women Handbook – How to Use the Law (1979)
  • Katherine Triantafillou & Lisa Leghorn, Have You Been Battered By the Man You Live With? (1978)