What is a preposition, and why does Italian make such a fuss about them?
A preposition is a small word that sets up a relationship between a noun (or pronoun) and the rest of the sentence — usually relationships of place ("on the table"), time ("in March"), means ("by train"), or purpose ("for you"). English has them too, of course. The problem is they almost never map one-to-one between languages: English "in" alone covers territory that Italian splits across in, a, and su depending on context, and vice versa. There's no shortcut around this — each Italian preposition has to be learned as its own small system of standard uses plus a handful of memorized exceptions. That's what these two lessons are for.
This lesson covers in, con, and su — the three simple prepositions (besides di/a/da, saved for later) that fuse with the definite article into a single word. Lesson 7 covers per, tra, and fra — the ones that never do.
Preposizioni articolate: prepositions + articles
Five simple prepositions fuse with a following definite article into one word — you'll never write "su la tavola", only "sulla tavola." Here's the complete grid. Di, a, and da are included for completeness (you'll meet their full usage in a future lesson) — today's focus is the in/con/su rows.
| il | lo | l' | la | i | gli | le | |
|---|---|---|---|---|---|---|---|
| di | del | dello | dell' | della | dei | degli | delle |
| a | al | allo | all' | alla | ai | agli | alle |
| da | dal | dallo | dall' | dalla | dai | dagli | dalle |
| in | nel | nello | nell' | nella | nei | negli | nelle |
| su | sul | sullo | sull' | sulla | sui | sugli | sulle |
Exception: con doesn't really belong in this table anymore
Con historically fused too (col, collo, colla, coi, cogli, colle), but in modern Italian only col (con + il) and coi (con + i) still see any real use — mostly in set phrases (caffè col latte) and a slightly journalistic register. The rest sound archaic today. Writing "con il" and "con i" separately is always correct and is what you should default to.
Exception: per, tra, and fra never fuse at all
No contraction exists for these three, ever — "per il," "tra i," "fra la" always stay as two words. One less thing to memorize for Lesson 7.
In
Base meaning: "in/inside." Its reach is much broader than that in practice.
| Use | Example |
|---|---|
| Countries, regions, continents, large islands | Vivo in Italia. Vado in Toscana. |
| Buildings / workplaces, as a destination | Vado in ufficio. Sono in biblioteca. |
| Mode of transport (general "by ___") | Vado in treno, in macchina, in bicicletta. |
| Months, years, seasons | Sono nato in maggio. Nel 2020. In inverno. |
| Language | Parliamo in italiano. |
| State / condition (fixed expressions) | Sono in ritardo. Siamo in vacanza. |
Named exception: cities and a handful of destinations take a, not in
The single biggest trap: a, not in, is used for cities and towns (Vado a Roma, not in Roma) — the region/country rule above only applies once you're above city scale. A short list of very common destinations are also fixed with a rather than in, essentially as memorized exceptions: a casa, a scuola, a teatro, a letto ("home," "school," "the theatre," "bed").
Con
Base meaning: "with." Three standard jobs:
| Use | Example |
|---|---|
| Accompaniment (with a person) | Esco con mia sorella. |
| Instrument/means (with a thing) | Taglio la carta con le forbici. |
| Manner (turns an abstract noun into "-ly") | Ascoltatemi con attenzione! (listen carefully) |
That manner use is worth internalizing on its own: where English reaches for an adverb ending in "-ly" (carefully, calmly, patiently), Italian very often prefers con + noun — con calma, con pazienza.
Su
Base meaning: "on/on top of." Three standard jobs:
| Use | Example |
|---|---|
| Physical position, on a surface | Il libro è sul tavolo. |
| Topic / subject matter ("about") | Un libro sulla storia di Roma. |
| Boarding transport you stand/sit up in | Sali sul treno, sull'autobus. |
Named exception: contraction with su is obligatory, not optional
Unlike con, there's no "detached" fallback here — you will never see "su la sedia." The fused form is the only correct form, full stop.
Named exception: su vs. di for topics
Both can mean "about." Di is the more natural default for well-established subjects (un libro di storia), while su/sulla tends to sound slightly more formal or emphatic, and is common when the topic itself is the whole point of the sentence ("Ho letto un articolo sulla crisi climatica."). Both are usually acceptable; this is a matter of nuance, not a hard rule.
Named exception: su vs. in for boarding transport
This directly refines the transport row in the in section above. In describes the general mode of travel ("Vado in treno" — I'm going by train), but the specific act of getting on distinguishes by vehicle type: su for vehicles you stand or sit up in and can walk around — trains, buses, planes, ships (Sali sul treno) — versus in for small enclosed vehicles you sit inside, like a car or taxi (Sali in macchina). The logic: a car is a container you get into; a train is a platform you get onto.
LearnAmo walks through the contraction table above with spoken examples.
Practice
Fill in the blank: "Vivo ___ Toscana." (I live in Tuscany.)
You're heading to Rome for the day. Which is correct?
Fill in the blank: "Ascoltatemi ___!" (Listen to me carefully!)
Which is the safest, most modern way to write "with the coffee"?
Fill in the blank: "Il gatto è ___ sedia." (The cat is on the chair. — sedia is feminine)
A taxi pulls up. How do you tell your friend to get in?
→ Open the reference cheat sheet for this lesson.