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Daniel J. Kollias received his law degree from Notre Dame Law School 1999. He is also a 1995 graduate of the University of Michigan, where he earned a B.A. in Economics.

After graduating law school, Dan worked as an Assistant State’s Attorney in the Cook County State’s Attorney’s Office. While there, he prosecuted dozens of criminal appeals in the Illinois Appellate Court. He also handled countless juvenile abuse and neglect cases at all stages in the legal process, from temporary custody through trial, disposition, permanency, and frequently, termination of parental rights and adoption.

After leaving the State’s Attorney’s Office, Dan successfully owned and managed a restaurant and bar in Elmhurst. He sold the business in 2002, and returned full time to the practice of law, opening an office in Wheaton as a sole practitioner. In 2009, he merged his practice into Mullen, Winthers & Kollias, P.C., where he was a partner for five years. Since 2014, he has been a partner in Kollias P.C.

Dan focuses his practice on family law, business planning, and estate planning. In the field of family law, he has represented thousands of clients in cases involving divorce, child custody, child support, maintenance, removal, and complex property division. Dan’s experience, both as a business owner and an attorney who handles business planning, provides him with unique insight into the particular issues which arise when small business owners find themselves going through a divorce.

Dan is also certified as a guardian ad litem in DuPage County. He is routinely appointed to investigate and report to the court regarding the best interests of the children in contested cases of child custody, visitation, and removal.

Dan represents family law clients in the appellate courts. On appeal, his clients have prevailed on issues such as post-divorce challenges to paternity; the non-modifiability of agreed orders; the classification of property as marital or non-marital; and whether money received from family members during a divorce should be treated as a loan or a gift. Some of those cases have established new legal precedent in Illinois, including the following:

In the field of business planning, Dan represents clients at all stages of the business life cycle, from business structure, organization, and formation, to succession planning, shareholder and operating agreements, purchase and sale of ownership interests, purchase and sale of assets, and dissolution. He also acts as registered agent for numerous clients, ensuring that routine matters like corporate minutes and annual reports are diligently maintained and filed in a timely manner. In the field of estate planning, Dan counsels clients on how to ensure that they and their loved ones are provided for in the event of incapacity or death, and how to minimize the effects of the estate tax. He prepares wills, simple and complex trusts, and powers of attorney.

Dan is an active member of the Du Page County Bar Association, and has given presentations at family law seminars. Dan speaks Greek fluently.

Prior Employment

  • Cook County State’s Attorney’s Office 1998 – 2001
  • Law Offices of Daniel J. Kollias, P.C., 2003 to 2009
  • Mullen, Winthers & Kollias, P.C. 2009 – 2014
  • Kollias P.C. 2014 to present.

Foreign Languages

  • Greek

Bar Associations


  • University of Notre Dame Law School - Juris Doctor - 1999
  • University of Michigan - B.A. Economics - 1995

Client Reviews

"Dan's expert handling of my divorce case was beyond my expectations. He takes control, documents your facts and summarizes options for you throughout the process. You will always get a timely response by email or phone. He will not forget the facts in your case or be uprepared for milestones along...


“Dan and his staff were very professional. They communicated to me in a timely manner. I felt very comfortable working with Dan. I would recommend Dan and his office to any one.”


“Daniel was able to help me expand my company with contracts. He was so nice and took time to really understand what I needed. He thought of things I had no idea I even needed to think about. He took time to explain things to me I was unsure. He wrote everything for me in a perfect time frame. I...


“I was referred to Dan Kollias for my divorce case by other family members who had used his services in the past. Dan worked very hard on what turned out to be a complicated case and was professional and helpful throughout. He kept me informed of status and changes and met with me whenever a...


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