A historical study has found that the Dutch royal house benefited from the country’s colonial policies in past centuries and helped the slave trade to survive.

The in-depth study, commissioned by King Willem-Alexander and conducted by Leiden University, showed the House of Orange-Nassau “actively supported Dutch colonialism for centuries, but only rarely determined colonial policy”, according to the university’s statement, published on Friday.

“The involvement of the House of Orange-Nassau was wholehearted and without any real reservations,” Dutch historians and human rights experts concluded after a three-year study looking at the period from 1600 to the present.

“The research leaves us in no doubt that the House of Orange shares responsibility for the survival over the centuries of the Dutch slave trade and slavery,” the study said, noting that most of the rulers showed no objections to slavery.

King Willem-Alexander said on Friday he was personally affected by the “explicit” conclusions of the study.

“It is a painful and confronting conclusion. A conclusion that affects me, even though I am three generations removed,” Willem-Alexander said in a speech at the presentation of the research.

“We know the effects of colonialism and slavery are still being felt today. Discrimination and economic exploitation unfortunately happen every day,” he added.

The study also showed that the royal family at times profited substantially from the colonial system, mostly from trade in the Dutch East Indies, modern-day Indonesia.

In the 19th century, for instance, profits accumulated to about $650m in modern terms, the researchers said.

On the other hand, the royal family earned “almost nothing” from the slave trade, the research showed.

Apologies without reparations The Dutch monarch, who in 2023 apologised for his ancestors’ lack of action against slavery, highlighted their lack of “counter-current leadership” in the face of colonialism.

Dutch historian Gert Oostindie, right, presents a volume of an independent study into the role of the House of Orange-Nassau in Dutch colonial history to King Willem-Alexander in Leiden, the Netherlands, on October 2, 2026 [Piroschka van de Wouw/Reuters] The House of Orange has ruled the Netherlands since the late 16th century, first as “stadtholders” who presided over the republic, and later as the royal house when the Netherlands became a monarchy.

For most of this time, the Dutch ruled over vast colonies in Southeast Asia and the Caribbean, including what is now Indonesia and Suriname. The findings could stir up the debate around reparations in the Netherlands.

The Dutch government apologised in 2022 after acknowledging the Dutch state bore responsibility for transatlantic slavery. King Willem-Alexander apologised the following year.

The government at the time ruled out reparations, instead creating a 200 million euro ($238m) fund for social initiatives, which anti-racism campaigners have dismissed as insufficient.

The National Institute for the Dutch Slavery Past and Heritage (NiNsee) lauded the king for commissioning the study but said it should lead to a next phase.

“Research impacts society when the new insights into the past contribute to awareness, dialogue, corrections and additions to our national history in the school curriculum and the conversation about responsibility and reparatory justice,” NiNsee director Bianca Groen Gallant said.

The Dutch played a major role in the global slave trade from the 17th century until the Netherlands abolished slavery in the second half of the 19th century.