It's over recent Census results, which showed a decline in the number of Welsh speakers.
The Welsh Government say the building remains open to staff and visitors as usual.
Cymdeithas are holding a peaceful protest at one of the entrances at the Welsh Government offices in Cardiff. The main reception remains open as usual to all staff and visitors.
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Representatives of the Conservative, Labour, Liberal Democrat, Plaid Cymru, Wales Greens and UKIP parties will debate on April 22.
A petition will be handed in at the Senedd later calling for rules to prevent the use by under 13's in care of social media sites.
Technology projects that promote the Welsh language are to get over £250,000 of funding to help encourage more use of in digital media.