In 1974, after an exhibition at the library in Aalborg, Carla Thonsgaard was invited by Lars Rostrup Boyesen to partake in the exhibition "Nordic Naïvists" held by the North Jutland Art Museum.

Subsequently she has worked with various different topics – trains moving are seen as a symbol of eternity; that she wants things to continue. Carla Thonsgaard has worked on a wide variety of mediums: she has decorated chocolate boxes, made book covers, posters, gable decorations and picture postcards of the city.

In the naïvistic art form, city images, which Carla Thonsgaard depicts historically though not topographically correct, are not uncommon. But in her paintings we also meet the critical and politically aware woman that she also is. In her paintings she raises her voice against the ungainly redevelopment of the city elements, against the excessive amount of cars on the beaches of the North Sea or against the German flag outnumbering the Danish flag. As a comment to the present time, she uses elements of nostalgia, as we see in e.g. a picture of Copenhagen showing the old Aalborg ferry which has long since disappeared, or the depiction of a beach with competing Danish and German flags.

In her paintings Carla Thonsgaard, who is very historically interested, tries to include as many recognisable elements as possible. If these elements were to be shown in a topographically correct manner however, they would become unrecognisable to the spectator. An example of this use of perspective is the painting "Randers" where we see the south side of the city. The painting shows the facade of Niels Ebbesen’s House, which is a physical impossibility.

In the painting "Højbro Plads, København" from 1990, the square is shown from the harbour. Blocks of flats surround it, and in the distance we see the familiar towers of Copenhagen in bright colours. The city is populated by super sized people, an effect that gives the spectator the impression of a toy city – the return to childhood.

Carla Thonsgaard deals with current issues in more ways than one. An example of this is the painting "Wedding". The picture clearly shows Prince Joakim and Princess Alexandra in their wedding dance, surrounded by applauding people in gala, and on the balcony we see the Royal Life Guard Band. This is not a socially critical painting, but a display of happiness connecting to a recent and joyous Danish event, and an opportunity to depict the diadems and colourful dresses of the ladies, and of course not least the wedding dress.