Complex Sentences (subordination)

A complex sentence is built from one main clause plus one or more subordinate clauses that depend on it — clauses that can't stand alone but instead do a job inside the bigger sentence (filling the object slot, modifying a noun, telling when or why). Where a compound sentence links equal partners with și or dar, a complex sentence makes one clause dependent on another, introduced by a subordinator like că, să, dacă, care, când, pentru că, or ca să. Building one well comes down to two practical choices: which connector introduces the clause, and which mood its verb takes. This page walks through both, and through the single habit that most separates fluent Romanian from English-transfer Romanian: using a finite să-clause where English would reach for "to + verb."

Building one step by step

Start with a main clause that needs completing, then attach the subordinate clause with the right connector. Take "I know" — Știu — which begs the question know what? You complete it with a clause introduced by că:

Now take "I want" — Vreau — which also begs want what? But "want" points at something not yet real, so its clause opens with să and the verb goes into the conjunctiv (subjunctive):

Compare the two side by side and the whole system is visible: same embedded event ("he comes tomorrow"), but Știu *că vine presents it as a fact I know, while Vreau **să vină* presents it as something I wish into being. The connector and the mood move together.

The core decision: că + indicative (facts) vs să + conjunctiv (wishes/goals)

This is the heart of Romanian subordination, and the rule is conceptual, not a memorized verb list. Ask one question about the embedded clause: is it presented as real — known, asserted, perceived, reported — or as irrealis — wanted, asked for, intended, doubted?

• Real → că + indicative. Verbs of knowing, saying, seeing, believing.
• Irrealis → să + conjunctiv. Verbs of wanting, asking, allowing, needing, intending.

The same verb can switch connectors when its meaning shifts. A spune normally reports a fact (spune că vine, "he says he's coming"), but used as a command it becomes irrealis and takes să (spune-i să vină, "tell him to come"):

One contrast worth flagging for learners coming from Spanish, French, or Italian: emotion verbs like a se bucura ("be glad") describe a reaction to something the speaker takes as real, so Romanian keeps că, not the subjunctive those languages would use:

The deeper map of which families of verbs and adverbials trigger which mood is on the subordination overview; the formation of the conjunctiv itself is on the subjunctive overview.

The infinitive gap: Romanian să where English uses "to"

This is the insight an English speaker most needs to internalize. In English, two verbs in a row are joined with the infinitive "to": I want *to leave, I'm trying to understand, she decided to stay, I came to help. Romanian almost never does this. Instead it uses a **finite *să-clause with a fully conjugated verb. "I want to leave" is not vreau a pleca but vreau să plec — literally "I want that I-leave."

The same applies to clauses of purpose — English "to" / "in order to," which becomes ca să (or just să):

Romanian does have a short infinitive (a merge, a vedea), and it survives in a few niches — after a putea it's optional (pot merge = pot să merg), in set phrases, and in elevated written style. But as a learner you should default to să and treat the bare infinitive complement as the marked, bookish choice. Reaching for an infinitive where Romanian wants să is the cardinal English-transfer error.

Other subordinators: dacă, care, când, pentru că

Beyond the că/să split, the everyday subordinators each introduce their own type of clause, and most take a comma when the subordinate clause comes first.

Dacă ("if/whether") introduces a condition or an indirect yes/no question:

Care ("who/which/that") introduces a relative clause modifying a noun, and it inflects for case (pe care, cu care, despre care):

Când ("when") and the causal pentru că ("because") introduce adverbial clauses, both with the indicative since they state facts:

Among the causal connectors, pentru că and fiindcă dominate speech, deoarece is more formal, and căci is literary — the nuances are laid out on the causal conjunctions page. Conditional and temporal connectors get fuller treatment on conditional and temporal conjunctions.

Comma placement

The practical rule: when the subordinate clause comes first, separate it with a comma (Dacă plouă, rămânem acasă; Când ajung, te sun). When the main clause comes first, a că- or să-completive object clause usually takes no comma (Știu că vine; Vreau să vină), while adverbial clauses (pentru că, deși, ca să) and non-restrictive relatives are typically set off by a comma. When in doubt, a fronted subordinate clause almost always wants its comma.

Common Mistakes

Using an English-style infinitive where Romanian needs să:

Calquing "to help" as a bare infinitive of purpose:

Putting să where the meaning is factual and demands că:

Using the subjunctive after an emotion verb (Romance transfer) when the event is real:

Dropping the comma before a fronted conditional clause:

Key Takeaways

• A complex sentence = a main clause + a dependent subordinate clause introduced by că, să, dacă, care, când, pentru că, or ca să.
• The core decision is că + indicative (facts) vs să + conjunctiv (wishes/goals) — test the meaning of the embedded clause, not a fixed verb list.
• Romanian replaces most English infinitives with a finite să-clause: vreau să merg, am venit ca să ajut. This is the most important habit to build.
• Emotion verbs keep că because the event is real — unlike the subjunctive of Spanish/French.
• A fronted subordinate clause takes a comma (Dacă plouă, rămânem acasă); a main-clause-first că/să object clause usually doesn't.