When do you use the congiuntivo in Italian?
Use the congiuntivo after expressions of opinion, doubt, emotion, wish and necessity — the trigger is in the first clause, before che. Italian uses it more than French does, and notably it follows penso che and credo che, where the equivalent verbs in French take the indicative.
Opinion takes it, unlike in French
This is the difference that catches French speakers. Penso che and credo che take the congiuntivo in Italian even when affirmative, because Italian treats an opinion as something other than an assertion of fact.
Penso che sia vero.
I think it's true.
Congiuntivo, even affirmative.
Credo che abbia ragione.
I think he's right.
So che è vero.
I know it's true.
Sapere asserts, so indicative.
Wish, doubt, emotion and necessity
Volere che, sperare che, dubitare che, essere contento che and bisogna che all trigger it. As in Spanish, an emotional reaction takes the congiuntivo even when the fact is certain.
Voglio che tu venga.
I want you to come.
Bisogna che tu parta subito.
You need to leave immediately.
Sono contento che tu sia qui.
I'm glad you're here.
Your presence is a fact; the reaction takes the congiuntivo.
Conjunctions that always take it
A fixed list of conjunctions demands the congiuntivo regardless of what follows: benché, sebbene, affinché, prima che, a meno che, purché. These are worth memorising outright because they are absolute.
Benché piova, esco.
Although it's raining, I'm going out.
Prima che sia troppo tardi.
Before it's too late.
Purché tu stia attento.
As long as you're careful.
Common mistakes
Penso che è vero.
Penso che sia vero.
Pensare che takes the congiuntivo in Italian even in the affirmative — this is where Italian and French diverge.
Voglio che vengo.
Voglio venire.
With the same subject in both halves, Italian uses the infinitive rather than che plus congiuntivo.
Benché è tardi, resto.
Benché sia tardi, resto.
Benché is an absolute trigger regardless of whether the fact is certain.
Frequently asked questions
Is the congiuntivo disappearing?
It is weakening in casual speech, particularly after pensare and credere, and you will hear penso che è. It remains fully standard in writing and in careful speech, and using the indicative there is noticed.
How is it different from the Spanish subjunctive?
The logic is the same but the trigger lists differ, and the clearest divergence is opinion: Spanish creo que takes the indicative while Italian credo che takes the congiuntivo. Do not transfer the Spanish habit directly.
Which forms should I learn first?
The present congiuntivo of essere, avere and the common irregulars — sia, abbia, faccia, possa, vada. Those cover most of what you will need, and the regular endings are straightforward once the irregulars are in place.