Placing se and si

You have met se and si as the little reflexive words that travel with verbs like dívat se ("to watch"), vrátit se ("to return"), or koupit si ("to buy oneself"). The hard part is not what they mean — it is where they go. Learners' instinct is to keep se glued to its verb, the way English keeps myself next to the verb. Czech does the opposite: se and si are second-position clitics, and they routinely sit far from the verb they belong to. This page is about the placement of se and si specifically — where they land in the clause and where they sit inside the cluster of little words. The general rule that governs all clitics is on Clitic Placement, and the mechanics of the past-tense auxiliary are on The Auxiliary in Second Position; here we zoom in on the reflexive.

se and si leave their verb behind

The key shock first. Se and si belong to a verb, but they do not have to stand next to it. They jump to the second slot of the clause — right after the first stressed unit — even if that strands them several words away from their verb.

In Včera se vrátil, the verb is vrátil at the end, but se sits in second position, right after the fronted adverb Včera. In Já se na to nedívám, se belongs to nedívám (the last word), yet it stands in slot two after the subject Já, with the whole phrase na to between them. The reflexive is faithful to its verb in meaning but loyal to second position in placement.

Where se and si sit inside the cluster

Often se/si are not alone in second position — a past or conditional auxiliary and one or two object pronouns crowd in there too. They line up in a fixed order, and the reflexive has a fixed seat in it:

So the reflexive comes after the auxiliary (bych, jsem) but before any object pronoun. Watch the order assemble:

Here the cluster is bych si to: auxiliary bych first, reflexive si second, accusative to last. You could not say Koupil si bych to — the auxiliary must lead.

The cluster jsem se shows the same order: auxiliary jsem before reflexive se. Putting se first here — Smál se jsem — is wrong.

After a fronted element, everything clusters in slot two

Front a single word — an adverb, a time expression, a conjunction — and the entire clitic chain piles in right after it, in that same order. The verb stays put.

The order is Ráno (fronted) + jsem (aux) + se (reflexive) + probudil (verb). Three things, one tight second-position cluster, with the participle probudil riding at the end.

Here se mi is reflexive + dative, both clustered after the fronted Dneska. The order reflexive-before-dative is exactly what the table predicts.

The contractions ses and sis

There is one spot where se and si physically fuse with the auxiliary. In the past tense, the second-person singular auxiliary jsi ("you") merges with a following se or si:

• jsi
  • se → ses
• jsi
  • si → sis

The separate jsi disappears, swallowed into the reflexive. This is obligatory in the standard language, not optional.

Without the contraction you would expect Vrátil jsi se / Koupil jsi si — and indeed you must not say those in careful Czech; the fused ses / sis is the correct form. (For a woman the participle is vrátila ses, koupila sis — the -a is on the participle, the contraction is unchanged.)

Why this is genuinely hard for English speakers

English has nothing like a second-position rule. Myself and object pronouns simply follow their verb: I watch it, I bought myself one. So the English instinct — put the little word next to the verb — produces wrong Czech almost every time a sentence starts with anything other than the verb. The fix is a habit, not a calculation: decide what goes first, then drop se/si (and the rest of the cluster) into second position in the fixed order, and let the verb land wherever it lands. The complete ordering of every clitic — including genitive and "long" forms — is laid out on The Order of the Clitic Chain; for the meaning difference between se and si themselves, see se vs si.

Common mistakes

The reflexive cannot wait next to its verb; it jumps to slot two right after the first element.

Inside the cluster the auxiliary (jsem) always precedes the reflexive (se).

Key takeaways

• Se and si are second-position clitics: they sit right after the first element of the clause, not beside their verb.
• Inside the cluster the order is auxiliary → se/si → dative pronoun → accusative pronoun: bych si to, jsem se.
• A fronted word pulls the whole chain into second position: Ráno jsem se probudil.
• The 2nd-sg. past auxiliary jsi fuses with the reflexive: jsi se → ses, jsi si → sis.