The good news about the irregular congiuntivo imperfetto is that there are far fewer truly irregular verbs than in the presente or congiuntivo presente. The endings stay regular; what varies is the stem. And once you know the rule — the congiuntivo imperfetto stem matches the imperfetto indicativo stem — most of the "irregulars" stop looking irregular at all.
The only verbs that genuinely break the pattern are essere, dare, and stare, with their short stems fo-, de-, ste-. Everything else — dire, fare, bere, porre, trarre, condurre — uses the same hidden Latin stems you already know from the imperfetto indicativo.
The general rule
For nearly every verb in Italian, the congiuntivo imperfetto stem is identical to the imperfetto indicativo stem. The endings then attach to that stem with the regular pattern (-essi, -essi, -esse, -essimo, -este, -essero for verbs whose imperfetto stem ends in -e; -assi for -are stems; -issi for -ire stems).
If you can produce dicevo, facevo, bevevo, ponevo, you can produce dicessi, facessi, bevessi, ponessi. The work is already done.
Essere — the only fully irregular paradigm
Essere is genuinely irregular. The stem fo- appears nowhere else in the modern paradigm and must simply be memorized. Together with avere (which is, in fact, regular here) it forms half of every congiuntivo trapassato, so this paradigm is essential.
| Person | essere |
|---|---|
| che io | fossi |
| che tu | fossi |
| che lui / lei | fosse |
| che noi | fossimo |
| che voi | foste |
| che loro | fossero |
Se fossi in te, accetterei subito quell'offerta di lavoro.
If I were you, I'd accept that job offer right away.
Pensavo che fosse più alto di così.
I thought he was taller than this.
Era strano che non foste ancora arrivati.
It was strange that you weren't there yet.
Avere — regular, despite appearances
Despite its many irregularities elsewhere, avere is perfectly regular in the congiuntivo imperfetto. The stem is av- (from the imperfetto indicativo avevo) and the endings are the standard -essi set.
| Person | avere |
|---|---|
| che io | avessi |
| che tu | avessi |
| che lui / lei | avesse |
| che noi | avessimo |
| che voi | aveste |
| che loro | avessero |
Se avessi i soldi, comprerei una macchina nuova.
If I had the money, I'd buy a new car.
Speravo che avesse il numero di telefono di Marco.
I was hoping she had Marco's phone number.
Hidden-stem verbs — the dicessi family
These verbs all hide a longer Latin stem under a shortened infinitive. The hidden stem reappears in the imperfetto indicativo and the congiuntivo imperfetto alike.
| Infinitive | Hidden stem | 1sg congiuntivo imperfetto |
|---|---|---|
| dire (to say) | dic- | dicessi |
| fare (to do/make) | fac- | facessi |
| bere (to drink) | bev- | bevessi |
| porre (to place) | pon- | ponessi |
| trarre (to draw/pull) | tra- | traessi |
| condurre (to lead/drive) | conduc- | conducessi |
| tradurre (to translate) | traduc- | traducessi |
The full paradigms simply attach the regular -essi endings to these stems:
| Person | dire | fare | bere |
|---|---|---|---|
| che io | dicessi | facessi | bevessi |
| che tu | dicessi | facessi | bevessi |
| che lui / lei | dicesse | facesse | bevesse |
| che noi | dicessimo | facessimo | bevessimo |
| che voi | diceste | faceste | beveste |
| che loro | dicessero | facessero | bevessero |
Se mi dicessi la verità, mi sentirei molto meglio.
If you told me the truth, I'd feel a lot better.
Vorrei che facesse meno freddo a Milano in inverno.
I wish it were less cold in Milan in winter.
Era ovvio che bevessero da ore.
It was obvious they'd been drinking for hours.
Ci tenevo che traducessi tu la lettera, non un programma.
I really wanted you to translate the letter yourself, not a program.
Dare and stare — the short stems
These two verbs use unusually short stems — de- and ste- — that produce double consonants when the endings attach. Memorize them as a pair; they pattern identically.
| Person | dare | stare |
|---|---|---|
| che io | dessi | stessi |
| che tu | dessi | stessi |
| che lui / lei | desse | stesse |
| che noi | dessimo | stessimo |
| che voi | deste | steste |
| che loro | dessero | stessero |
Se mi dessi una mano, finiremmo in mezz'ora.
If you gave me a hand, we'd finish in half an hour.
Pensavo che stessero ancora a Roma.
I thought they were still in Rome.
Vorrei che mia nonna stesse meglio.
I wish my grandmother were doing better.
A short note on benché, sebbene, nonostante + past
When concessive conjunctions like benché, sebbene, and nonostante introduce a past situation, they take the congiuntivo imperfetto (or trapassato) just like any other subjunctive trigger.
Benché fosse stanchissimo, non voleva andare a letto.
Even though he was exhausted, he didn't want to go to bed.
Sebbene avessero poco tempo, riuscirono a visitare i musei principali.
Although they had little time, they managed to visit the main museums.
Nonostante piovesse, decidemmo di partire lo stesso.
In spite of the fact that it was raining, we decided to leave anyway.
Common mistakes
❌ Se ero in te, accetterei l'offerta.
Incorrect — counterfactuals require the congiuntivo imperfetto. The imperfetto indicativo (ero) doesn't trigger a hypothetical reading.
✅ Se fossi in te, accetterei l'offerta.
Correct — fossi marks the unreal, hypothetical condition.
❌ Vorrei che facessi bel tempo domani.
Incorrect — domani is future. With a present matrix referring to the future, use the congiuntivo presente: faccia.
✅ Vorrei che facesse bel tempo domani.
Use the congiuntivo imperfetto in counterfactual or hypothetical contexts; here vorrei + congiuntivo imperfetto expresses an unrealistic wish.
❌ Pensavo che diceva la verità.
Incorrect — past matrix verbs of opinion (pensavo, credevo) require the subjunctive in the subordinate, not the indicative.
✅ Pensavo che dicesse la verità.
Correct — pensavo + congiuntivo imperfetto.
❌ Se mi davi una mano, avremmo finito prima.
Incorrect — Italian counterfactuals don't use the imperfetto indicativo in the se-clause (this is colloquial English/Spanish-style usage).
✅ Se mi dessi una mano, finiremmo prima.
Correct — present counterfactual: se + congiuntivo imperfetto + condizionale presente.
❌ Sebbene era stanco, non voleva dormire.
Incorrect — sebbene always takes the congiuntivo, never the indicativo.
✅ Sebbene fosse stanco, non voleva dormire.
Correct — concessive sebbene + congiuntivo imperfetto.
Key takeaways
For irregular congiuntivo imperfetto, the stem-rule is decisive: whatever stem the imperfetto indicativo uses, the congiuntivo imperfetto uses the same one. That collapses dire, fare, bere, porre, trarre, condurre, tradurre, and dozens of compounds into one rule. Only essere (fossi), dare (dessi), and stare (stessi) genuinely break the pattern — and even those follow the regular ending set.
With this tense plus the regular paradigms, you are ready for the congiuntivo trapassato — which is just avessi/fossi + participio passato — and for the heart of the Italian conditional system, conditional sentences.
Now practice Italian
Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.
Open the Italian course →Related Topics
- Congiuntivo Imperfetto: Regular VerbsB1 — How to form the regular congiuntivo imperfetto across all three conjugations — and why this is the tense that finally makes the subjunctive feel natural.
- Congiuntivo Presente: Irregular VerbsB1 — Italian's irregular present subjunctives are not random — almost every one is built on the first-person singular of the indicative. Learn the rule and you'll never have to memorize an irregular subjunctive again.
- Congiuntivo Trapassato: Formation and UsageB1 — The most useful subjunctive tense in everyday Italian — how to form the congiuntivo trapassato and why it lives at the heart of the type-3 counterfactual.
- Congiuntivo Triggers: OverviewB1 — A complete catalog of when Italian demands the subjunctive — verbs of opinion, doubt, desire, emotion, impersonal expressions, and the conjunctions that always take it.