Catalan has several ways to put a boundary at the beginning of an event. Començar a + infinitive is the neutral, all-purpose choice; posar-se a + infinitive presents a person or force as entering an activity, often deliberately or suddenly; arrencar a + infinitive makes the onset feel abrupt, energetic, or explosive. All three are standard, but they offer different viewpoints rather than three word-for-word translations of English “start.”
The finite verb carries person, number, tense, and mood. The infinitive remains unchanged, and the linking a is obligatory: comencem a parlar, es van posar a riure, arrencarà a córrer. These constructions are neutral unless a different register is explicitly labeled below.
The three constructions at a glance
| Construction | Usual viewpoint | Typical subjects |
|---|---|---|
| començar a + infinitive | neutral beginning; a new phase starts | people, events, processes, weather |
| posar-se a + infinitive | entry into an activity, often with initiative or suddenness | mainly animate agents; also weather and other dynamic forces |
| arrencar a + infinitive | sudden, forceful outbreak | people and things capable of a salient onset |
A mig matí ha començat a nevar i la carretera s'ha emblanquinat de seguida.
It started snowing in the middle of the morning, and the road quickly turned white.
Quan tothom va callar, la Laia es va posar a explicar què havia passat.
When everyone fell silent, Laia started explaining what had happened.
En sentir el tro, la criatura va arrencar a plorar.
On hearing the thunder, the child burst into tears.
The first example merely locates the onset. The second shows an agent entering an activity. The third turns the beginning itself into a vivid event. English often flattens all three to “started,” so the Catalan choice must come from the intended scene, not from the English verb.
Present forms and spelling
The following complete present model shows where agreement appears. Stress falls on the stem in the singular and third-person plural forms, but on the ending in comencem, comenceu, posem, poseu, arrenquem, and arrenqueu.
| Person | començar a parlar | posar-se a parlar | arrencar a parlar |
|---|---|---|---|
| jo | començo a parlar | em poso a parlar | arrenco a parlar |
| tu | comences a parlar | et poses a parlar | arrenques a parlar |
| ell / ella / vostè | comença a parlar | es posa a parlar | arrenca a parlar |
| nosaltres | comencem a parlar | ens posem a parlar | arrenquem a parlar |
| vosaltres / vós | comenceu a parlar | us poseu a parlar | arrenqueu a parlar |
| ells / elles / vostès | comencen a parlar | es posen a parlar | arrenquen a parlar |
The alternations c/ç in començar and c/qu in arrencar preserve the same consonant sound before different vowels: començo but comencem; arrenco but arrenquem. The cedilla never appears before e or i. In posar-se, the reflexive pronoun agrees with the subject; it is not an optional decoration.
Comenceu a llegir pel segon capítol; el primer només és una introducció.
Start reading with the second chapter; the first is only an introduction.
Ens posem a preparar el sopar o encara esperem la Marta?
Shall we start making dinner, or are we still waiting for Marta?
Quan arrenquen a tocar, la plaça sencera es posa a ballar.
When they launch into playing, the whole square starts dancing.
Time, aspect, and mood
Any ordinary finite tense can locate the onset. The present can describe an onset now or a scheduled one; the periphrastic past presents a completed entry into the activity; the imperfect views the beginning as background, repeated behavior, or an interrupted development. The subjunctive appears only when the larger clause presents the onset as desired, doubted, pending, or otherwise unasserted.
Demà començarem a instal·lar les finestres noves.
Tomorrow we'll start installing the new windows.
Cada cop que li feien aquella pregunta, es posava a mirar per la finestra.
Every time they asked him that question, he would start looking out the window.
No crec que comencin a temps si encara no tenen els permisos.
I don't think they'll start on time if they still don't have the permits.
The subjunctive comencin follows from the speaker's nonassertion after no crec que. There is no rule saying that an inchoative periphrasis itself “takes the subjunctive.” Viewpoint, discourse time, and assertion status belong to the whole clause.
Do not confuse va començar a treballar with the shape of the periphrastic past. Here va començar is itself the past of començar, and a treballar is its complement. By contrast, va treballar is simply “worked”; inserting a would produce present anar plus an infinitive in a different construction. See the past and present forms of anar.
What each construction highlights
Començar a accepts the broadest range of subjects and infinitives. It is equally natural with intentional acts, uncontrolled processes, changes of state, and perception.
A poc a poc començo a entendre per què van cancel·lar el projecte.
Little by little, I'm beginning to understand why they canceled the project.
Posar-se a typically profiles an active transition. With a human subject it often suggests “get down to” or an abrupt change of behavior. With weather, posar-se a ploure is an established way to present the onset as sudden. It does not mean that the rain has intentions.
Tan bon punt vam arribar a casa, ens vam posar a endreçar-ho tot.
As soon as we got home, we started tidying everything up.
Just quan sortíem, es va posar a ploure a bots i barrals.
Just as we were leaving, it started pouring.
Arrencar a is more lexically restricted. It is especially natural with córrer, riure, plorar, parlar, cantar, or a machine beginning to operate. It is vivid (informal or narrative), though it also occurs in journalistic prose.
Després d'uns segons de silenci, el públic va arrencar a aplaudir.
After a few seconds of silence, the audience burst into applause.
Using arrencar a for a slow, unremarkable routine can sound overdramatic. Dilluns començo a treballar a les nou is neutral; dilluns arrenco a treballar a les nou can suggest an energetic launch and is not the default timetable statement.
Weak pronouns
A weak pronoun belonging to the infinitive can often appear before the finite verb or attach to the infinitive: ho comença a entendre / comença a entendre-ho. Low attachment is always a clear choice with these constructions. With posar-se a, remember that the finite verb already has its reflexive pronoun.
La recepta, la començarem a preparar quan arribi tothom. / Començarem a preparar-la quan arribi tothom.
We'll start preparing the recipe when everyone arrives.
En Pau es va posar a explicar-m'ho sense que jo li ho preguntés.
Pau started explaining it to me without my asking him.
The cluster m'ho attaches to explicar as explicar-m'ho. More complex climbing patterns are covered on the weak-pronoun placement page.
Mini-dialogue
—Quan començareu a pintar el menjador? —Aquest vespre. Primer ens posarem a tapar els mobles i, si tot va bé, demà arrencarem a pintar de bon matí.
—When will you start painting the dining room? —This evening. First we'll get to covering the furniture and, if all goes well, tomorrow we'll launch into painting early in the morning.
The neutral question uses començar a. The answer moves from deliberate preparation with posar-se a to an energetic launch with arrencar a. No English progressive is needed to license any of them.
Regional and register notes
These three constructions are understood across the Catalan-speaking area. Present and subjunctive endings vary by dialect—forms such as comence and arranque occur (regional: Valencian) where Central Catalan has començo and arrenco—but the construction still requires a + infinitive. The forms taught in the table are the Central Catalan baseline. Principiar a exists (formal, literary, and regionally marked), but it is not the everyday default.
Common Mistakes
1. Omitting the linking preposition.
❌ Comencem preparar el dinar ara mateix.
Incorrect—the inchoative construction requires a before the infinitive.
✅ Comencem a preparar el dinar ara mateix.
Let's start preparing lunch right now.
2. Copying an English progressive after the preposition.
❌ S'ha posat a plorant quan ha llegit el missatge.
Incorrect—after a, Catalan uses the infinitive, not the gerund.
✅ S'ha posat a plorar quan ha llegit el missatge.
She started crying when she read the message.
3. Dropping the reflexive pronoun from posar-se a.
❌ La mainada va posar a córrer cap a la porta.
Incorrect in this meaning—entry into the activity requires posar-se.
✅ La mainada es va posar a córrer cap a la porta.
The children started running toward the door.
4. Confusing the periphrastic past with anar a + infinitive.
❌ Ahir va a començar la reforma.
Incorrect for a completed past—the a cannot follow periphrastic-past va.
✅ Ahir va començar la reforma.
The renovation began yesterday.
5. Choosing mood from a memorized trigger alone.
❌ Sé que comencin a les nou.
Incorrect—known, asserted information takes the indicative.
✅ Sé que comencen a les nou.
I know they start at nine.
Key Takeaways
Use començar a for a neutral beginning, posar-se a for entering an activity, and arrencar a for a forceful onset. Conjugate only the first verb, retain the required a, and keep the second verb in the infinitive. Choose tense and mood from the clause's timeline and assertion status, not from an English translation.
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