Interessere sig | Danish Grammar

Interessere sig is how Danish says "to be interested". The crucial twist for English speakers: Danish has no single intransitive verb meaning "I am interested" — it builds the idea reflexively, "I interest myself". Drop the reflexive pronoun and you say something different: plain interessere (without sig) means "to interest someone else". The reflexive is therefore not optional decoration — it is what makes the verb mean what you intend.

Principal parts

Infinitive	Present	Past	Past participle	Imperative
(at) interessere sig	interesserer sig	interesserede sig	interesseret sig	interessér dig!

Interessere is a regular weak verb of the -ede class: past interesserede, participle interesseret. The reflexive pronoun changes with the subject — mig, dig, sig, os, jer, sig — but the verb form itself does not.

💡

Danish verbs never change for person or number, but the reflexive pronoun does: jeg interesserer *mig, du interesserer dig, han interesserer sig, vi interesserer os, I interesserer jer, de interesserer sig.

The reflexive is obligatory

Compare the two verbs side by side. Without sig, interessere is transitive: its subject is the thing that arouses interest, and it needs a different object — the person who becomes interested. With sig, the subject is the interested person.

Jeg interesserer mig for klassisk musik.

I'm interested in classical music. (reflexive — I am the interested one)

Emnet interesserer mig ikke.

The topic doesn't interest me. (non-reflexive — the topic acts on me)

Det her vil sikkert interessere dig.

This will surely interest you. (non-reflexive — 'it' interests 'you')

💡

The test: who is interested? If the subject is the interested person, you need sig (interessere sig for). If the subject is the thing arousing interest, drop sig (X interesserer mig). This is the same machinery as other reflexive verbs — see verbs/reflexive-verbs.

interessere sig for — the standard construction

To name what you're interested in, Danish uses the preposition for: interessere sig *for noget*. This pairing is fixed; the preposition is not negotiable (see prepositions/verbs-prepositions-reference).

Hun har altid interesseret sig for politik.

She has always been interested in politics.

Børnene interesserer sig mest for dinosaurer lige nu.

The kids are most interested in dinosaurs right now.

Han interesserede sig ikke det mindste for fodbold.

He wasn't interested in football in the slightest.

The perfect: har interesseret sig

The perfect is built with have: har interesseret sig. The reflexive pronoun stays with its subject; in a main clause it typically follows the finite verb.

Jeg har altid interesseret mig for sprog.

I've always been interested in languages.

De har aldrig rigtig interesseret sig for naboernes liv.

They've never really taken an interest in the neighbours' lives.

The adjectival alternative: at være interesseret i

Danish very often expresses the same idea with the past participle used as an adjective: være interesseret i noget ("be interested in something"). Note the preposition switches from for to i here. This construction is at least as common as the reflexive verb and a touch more neutral.

Jeg er meget interesseret i jobbet.

I'm very interested in the job. (være interesseret i)

Er du interesseret i at komme med i aften?

Are you interested in coming along tonight?

💡

Two ways to say "interested in", with different prepositions: interessere sig for (the reflexive verb) vs være interesseret i (the adjective). Mixing the prepositions — interessere sig i or interesseret for — is a classic learner slip.

The word family

The root spreads across the lexicon, and knowing the family helps:

Word	Type	Meaning
en interesse	noun	an interest
interessant	adjective	interesting
interesseret (i)	adjective / participle	interested (in)
uinteresseret	adjective	uninterested, indifferent

Det lyder rigtig interessant — fortæl mig mere.

That sounds really interesting — tell me more.

Hun har en stor interesse for gammel arkitektur.

She has a great interest in old architecture. (noun: interesse for)

Common Mistakes

1. Dropping the reflexive sig/mig/dig. Without it, the sentence either fails or flips meaning.

❌ Jeg interesserer for klassisk musik.

Wrong — without the reflexive, the verb has no proper subject for this meaning.

✅ Jeg interesserer mig for klassisk musik.

I'm interested in classical music.

2. Mixing up the prepositions. The verb takes for; the adjective takes i.

❌ Jeg er interesseret for jobbet.

Wrong preposition — the adjective interesseret takes i.

✅ Jeg er interesseret i jobbet.

I'm interested in the job.

3. Using interesseret for / interessere sig i. The mirror error.

❌ Hun interesserer sig i politik.

Wrong preposition — the reflexive verb takes for, not i.

✅ Hun interesserer sig for politik.

She's interested in politics.

4. Wrong reflexive person. The pronoun must agree with the subject — jeg needs mig, not sig.

❌ Jeg interesserer sig for fysik.

Wrong — first person needs mig, not the third-person sig.

✅ Jeg interesserer mig for fysik.

I'm interested in physics.

5. Confusing the two verbs. X interesserer mig (X interests me) is not the same as jeg interesserer mig for X (I'm interested in X).

❌ Jeg interesserer mig matematik.

Incomplete — to be interested in something you need 'mig for'.

✅ Matematik interesserer mig. / Jeg interesserer mig for matematik.

Maths interests me. / I'm interested in maths.

Key Takeaways

💡

Interessere sig (weak -ede: interesserer sig / interesserede sig / har interesseret sig) = "be interested", and the reflexive pronoun is obligatory — without it, interessere means "to interest someone else". Name the topic with interessere sig for. The adjectival alternative være interesseret i says the same thing with a different preposition. Don't cross the wires: verb → for, adjective → i.

Now practice Danish

Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.

Start learning Danish→