Per vs A vs Di Before Infinitive: Purpose and Verb Complement

When an Italian sentence has an infinitive — fare, partire, capire, imparare — there are three prepositions that can introduce it: per, a, or di. They are not interchangeable. Each does a different job.

Per + infinitive marks explicit purpose — "in order to do." This is the productive, predictable construction: any time you want to say why you are doing something, per is the connector. Vado al supermercato per comprare il pane (I'm going to the supermarket in order to / to buy bread).

A + infinitive and di + infinitive are lexical complements — they appear after specific verbs that govern those prepositions. Comincio a studiare (I start studying) uses a because cominciare is a verb that takes a + infinitive. Spero di vincere (I hope to win) uses di because sperare takes di + infinitive. The choice between a and di is not semantic — it depends on the verb.

This page disentangles the three constructions, gives the diagnostic test for per, and lists the contrasts where confusion is most common. The B1 designation reflects that this is not a beginner topic: it requires you already know which verbs take a and which take di. The challenge here is recognizing when neither is right and per is needed instead.

1. The three constructions, side by side

The crucial insight: per is productive — it can attach to any verb to express the purpose of an action. A and di are lexically restricted — they appear only with specific verbs that the dictionary marks as taking a or di before an infinitive.

If you want to say "I do X to do Y" where Y is the purpose, use per. If you want to say "I [verb] doing Y" where the structure depends on the specific verb, you need to know which preposition that verb selects.

2. Per + infinitive: explicit purpose

The cleanest of the three constructions. Per + infinitive translates English "in order to" or "to" in the purpose sense.

The construction is fully productive: any main verb can take per + infinitive if you want to add a purpose. The test "in order to" reliably distinguishes per from the lexical a / di uses.

A fine point: in literary or formal Italian, al fine di + infinitive and allo scopo di + infinitive are alternatives to per with the same "in order to" meaning. They are heavier and more formal — fine in academic writing, stilted in conversation. Per is the everyday default.

3. A + infinitive: verb complement

When a verb is lexically marked as taking a + infinitive, you must use a — there is no semantic choice. The list of a-verbs has to be memorized.

The verbs are clustered semantically — inceptive (cominciare, iniziare, mettersi), causative (aiutare, costringere, obbligare, incoraggiare), motion-with-purpose (andare, venire) — but the rule that links them all is structural: each one selects a before the infinitive that follows.

The verb andare a + infinitive is special: it expresses both motion and purpose ("go and do"). In this case the a could be interpreted as either the lexical a of andare or the purpose-a. In practice, the construction is fixed: vado a comprare il pane (I'm going to buy bread) — the a is required, and there's no debate about whether it's purpose or complement.

4. Di + infinitive: verb complement

The third construction. Many high-frequency Italian verbs select di + infinitive.

Like the a-verbs, this list is lexical: each verb selects the di + infinitive construction, and there is no semantic shortcut for predicting which preposition a verb takes.

5. The crucial contrast: per vs di / a

The three constructions can produce nearly identical-looking sentences. Compare:

In each pair, the same infinitive (vedere, parlare, arrivare, comprare) appears with different prepositions because the function is different. Per marks the purpose of an independent action; di and a are baked into specific verb constructions.

6. The "pronto a / pronto per" alternation

A specific case worth flagging. The adjective pronto (ready) takes either a + infinitive or per + infinitive, with subtle nuance.

• Pronto a + infinitive is the more standard form: sono pronto a partire (I'm ready to leave).
• Pronto per + infinitive is also heard, especially in colloquial speech: sono pronto per partire.

Both are acceptable; a is slightly more standard in writing. Don't lose sleep over the choice — both are heard from natives.

A similar alternation exists with a few other adjectives — adatto a / adatto per (suitable for), utile a / utile per (useful for) — and again, the a form is slightly more standard but both are common.

7. Some verbs allow both per and di / a (with different meanings)

A small number of verbs can take more than one preposition, and the meaning shifts.

Pensare:

• Pensare a + person/thing = to think about (have someone in mind): penso a te (I think about you).
• Pensare di + infinitive = to plan to, to be considering: penso di partire (I'm thinking of leaving).

Decidere:

• Decidere di + infinitive = to decide to: ho deciso di partire (I've decided to leave).
• Decidersi a + infinitive = to make up one's mind to (with reflexive): mi sono deciso a partire (I've finally made up my mind to leave). The reflexive form adds an "after deliberation" nuance.

Provare:

• Provare a + infinitive = to try to (attempt): provo a chiamarlo (I'll try calling him).
• Provare di / con qualcosa — different constructions, not directly comparable.

Finire:

• Finire di + infinitive = to finish doing: ho finito di mangiare (I finished eating).
• Finire per + infinitive = to end up doing (after a sequence of events): ho finito per accettare (I ended up accepting).

The finire per construction is especially useful and worth memorizing. It expresses an outcome that resulted after multiple steps or considerations: ho finito per accettare la proposta dopo lunghe trattative (I ended up accepting the proposal after long negotiations).

8. Verbs that take the bare infinitive (no preposition)

A reminder: there's a fourth option — verbs that take the bare infinitive with no preposition at all. These are the modal verbs and a small set of preference verbs.

These verbs do not take per, a, or di before the infinitive. Voglio per partire, voglio di partire, voglio a partire are all wrong; voglio partire is correct.

This bare-infinitive class is one of the cleaner sub-rules. If your verb is a modal or a preference verb, no preposition.

9. A diagnostic flowchart

When you have an infinitive in your sentence and need to choose a preposition, ask in this order:

1. Is the infinitive expressing the purpose of the main action? ("In order to" works in English.) → Use per.
2. Is the main verb a modal (volere, potere, dovere, sapere)? → No preposition; use the bare infinitive.
3. What preposition does the main verb lexically select? Look it up. → Use a or di as the verb's dictionary entry specifies.

Most cases fall cleanly into one of the three.

10. Per + infinitive in the past

A useful extension. Per + past infinitive (per aver fatto, per essere venuto) expresses the reason for something that happened — "for having done."

This is one of the most useful constructions in formal and semi-formal Italian. The structure is per + aver(e) / esser(e) + past participle, and the meaning is "for having + verb-en."

11. Common mistakes

12. The deeper logic

Why do Italian and other Romance languages distinguish between purpose-per and lexical-a / di? The historical reason is that per descends from Latin per (through, by means of, for the sake of), which already carried a goal-oriented meaning. A and di descend from Latin ad (to, toward) and de (from, of), which carried more relational meanings.

Over time, per specialized into the productive marker of purpose — I do X for the sake of doing Y. A and di were absorbed into the lexical entries of specific verbs, where they no longer carry independent meaning but simply serve as connectors.

The takeaway for learners: per is the only one of the three with semantic content of its own. A and di in front of an infinitive are essentially grammatical markers — they tell you which verb governs the construction, not what the relationship between the actions means. So:

• Studio per imparare — the per tells you that learning is the purpose of studying.
• Comincio a imparare — the a doesn't mean anything on its own; it's just what cominciare takes.
• Spero di imparare — the di doesn't mean anything on its own; it's just what sperare takes.

If you internalize this asymmetry — per is meaningful, a and di are lexical — the system clicks into place.

13. Summary

The mental model:

1. Per is meaningful. When you want to say why, use per.
2. A and di are lexical. They depend on the verb. Look up which verb takes which.
3. Modals take the bare infinitive. No preposition with volere, potere, dovere, sapere.

If you know which verb you're using and what its preposition is, the construction follows automatically. The hard work is learning the verb-preposition pairings — which is the work of Verbs with Specific Prepositions. Once that is in place, distinguishing purpose-per from lexical-a / di becomes mechanical.

Where to go next

• Verbs with Specific Prepositions — the reference for which Italian verbs take which prepositions, indispensable for choosing between a and di before an infinitive.
• A with Verbs — the deeper page on the a + infinitive verb class.
• Di with Verbs — the deeper page on the di + infinitive verb class.
• The Preposition A: Overview — the full inventory of a's uses, including direction, time, indirect-object marker, and verb complements.
• The Preposition Di: Overview — the full inventory of di's uses, including possession, topic, and verb complements.
• Prepositions: Overview — the broader map of the Italian preposition system.