One of the quiet hallmarks of good Czech is knowing that "he became a doctor" is stal se lékařem, not stal se lékař. The new role goes into the instrumental — the same seventh case you already use for tools and means — and English gives you no warning that this is coming, because English just says "a doctor" in both "he is a doctor" and "he became a doctor." This page is about the predicate instrumental: the case you put a profession, role, or new state into after verbs of being and becoming.
The core idea: a role is something you act as
Think back to the instrumental's home meaning — kým? čím?, "by means of whom/what." A predicate noun in the instrumental treats the person as someone functioning in a capacity: he serves as a doctor, she works as a teacher. It is the case of the role you fill, not the label of who you are. That single intuition — identity is nominative, role is instrumental — predicts almost everything below.
After stát se: instrumental is obligatory
With stát se (to become — perfective; imperfective stávat se) you have no choice. Becoming is by definition entering a new role or state, so the complement must be instrumental. This is the rule English speakers break most often.
Po studiích se stal lékařem v pražské nemocnici.
After his studies he became a doctor in a Prague hospital. (lékařem — instrumental, obligatory after stát se)
Chci se jednou stát učitelkou na základní škole.
One day I want to become a primary-school teacher. (učitelkou — feminine instrumental in -ou)
Novák se stal ředitelem firmy už ve třiceti.
Novák became the company director at just thirty. (ředitelem)
Po volbách se Havel stal prezidentem.
After the elections, Havel became president. (prezidentem)
Note the reflexive se: stát se is reflexive, and se is a second-position clitic, so it slides leftward — stal *se lékařem, but chci **se stát učitelkou (the *se jumps in front of the infinitive cluster). And because stát se is perfective, its present-tense forms carry future meaning: stane se means "will become": Stanu se lékařem. ("I will become a doctor.")
Adjectives behave the same way after stát se — they too go instrumental, not nominative:
Po vydání románu se přes noc stal slavným.
After the novel came out, he became famous overnight. (slavným — adjective in the instrumental too)
After být: instrumental or nominative — and they differ
With být ("to be") you genuinely have a choice, and the choice carries meaning. The nominative classifies — it tells you what category someone belongs to. The instrumental presents the same fact as a role or function, often something acquired, professional, or true for a phase of life.
| Form | Reading | Feel |
|---|---|---|
| Je učitel. (nominative) | "He's a teacher." | Plain classification — the everyday, neutral choice in speech. |
| Je učitelem. (instrumental) | "He is/serves as a teacher." | Stresses the role/function; more bookish, more formal. |
In the present tense, the nominative is the unmarked everyday form — Je učitel, Je inženýr, Je doktorka are what people say. The instrumental (je učitelem) is correct but leans formal, official, or written, and it foregrounds the job as a function. In the past tense, the balance flips: the instrumental is very natural and often preferred, because a past profession reads as a phase of life — Byl vojákem, Dlouho byla učitelkou sound better than the bare nominatives.
Můj otec je inženýr, ale původně byl učitelem.
My father is an engineer, but he was originally a teacher. (present nominative inženýr; past instrumental učitelem)
Dlouho byl vojákem, než odešel do civilu.
He was a soldier for a long time before leaving for civilian life. (vojákem — past, phase of life)
Když vyrostu, chci být hasičem.
When I grow up, I want to be a firefighter. (hasičem — being in a future/aspirational role)
jako + nominative — the third option
There is also jako ("as"), which takes the plain nominative and means roughly the same as the role-instrumental: Pracuje jako učitel = Je učitelem = "he works as / is a teacher." Use jako when you literally mean "in the capacity of."
Pracuje jako překladatel, ale vystudoval práva.
He works as a translator, but he studied law. (jako + nominative překladatel)
Identity stays nominative
When you point at someone and say who they are — a name, a relationship, a "this is…" — that is pure identity, and it stays in the nominative. Never put an identifying to je phrase into the instrumental.
To je můj starší bratr, je zubařem ve Zlíně.
This is my older brother; he's a dentist in Zlín. (identity to je … bratr — nominative; role je zubařem — instrumental)
That sentence shows both at once: bratr stays nominative because it answers "who is this?", while zubařem is instrumental because it states the role he fills. Nationality and other fixed, defining traits are likewise nominative: Je Čech ("He's Czech"), never je Čechem in neutral speech.
jmenovat and zvolit: appointing into a role
A small but high-value group of verbs names the result of an appointment or election with the instrumental — they put someone into a role. The two everyday ones are jmenovat (to appoint/name) and zvolit (to elect). The pattern is jmenovat / zvolit + accusative person + instrumental role.
Jmenovali ho ředitelem celé školy.
They appointed him director of the whole school. (ho — accusative; ředitelem — instrumental of the resulting role)
Na schůzi ji zvolili předsedkyní spolku.
At the meeting they elected her chair of the association. (předsedkyní — soft feminine instrumental in -í)
The logic is identical to stát se: an appointment turns a person into something, and Czech marks that something as a role with the instrumental. The same holds for udělat in the sense of "make someone into" and for zvát/nazývat ("to call someone something").
The instrumental endings you need
These are just the ordinary singular instrumental endings — nothing special about predicates. The most common profession endings:
| Gender / type | Nominative | Instrumental |
|---|---|---|
| masc. (hard & soft) | inženýr, lékař, učitel | inženýrem, lékařem, učitelem (-em) |
| masc. in -a | předseda | předsedou (-ou) |
| fem. hard | učitelka, doktorka | učitelkou, doktorkou (-ou) |
| fem. soft | předsedkyně | předsedkyní (-í) |
Common mistakes
❌ Po studiích se stal doktor.
Incorrect — after stát se the role must be instrumental, not nominative.
✅ Po studiích se stal doktorem.
Correct: he became a doctor.
❌ Chci se stát učitelka.
Incorrect — nominative left in place after stát se.
✅ Chci se stát učitelkou.
Correct: I want to become a teacher.
❌ Jmenovali ho ředitel.
Incorrect — the resulting role after jmenovat takes the instrumental.
✅ Jmenovali ho ředitelem.
Correct: they appointed him director.
❌ To je můj bratrem.
Incorrect — an identifying 'to je…' is plain nominative, not instrumental.
✅ To je můj bratr.
Correct: this is my brother.
❌ Po vydání knihy se stal slavný.
Incorrect — adjectives after stát se also go instrumental.
✅ Po vydání knihy se stal slavným.
Correct: after the book came out he became famous.
Key takeaways
- stát se ("become") + role/state → always instrumental: stal se lékařem, stala se slavnou.
- být
- profession → nominative is the everyday default (je učitel); the instrumental (je učitelem) is the more formal, role-focused option and is especially natural in the past (byl vojákem).
- Identity — names, relationships, "this is…", nationality — stays nominative: to je můj bratr, je Čech.
- jmenovat / zvolit + accusative + instrumental for appointing or electing someone into a role: zvolili ji předsedkyní.
- The endings are the ordinary singular instrumental: masculine -em, feminine -ou (soft feminine -í).
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Start learning Czech→Related Topics
- Predicate Nominative with BýtA2 — Why the complement of the verb 'to be' usually stands in the nominative, and when the instrumental competes.
- The Instrumental of MeansA2 — Using the instrumental to express the tool or means by which something is done.
- Common Mistakes: Profession with býtB1 — Saying je učitel where the careful standard wants the instrumental je učitelem.
- Common Mistakes: Using the Nominative EverywhereA2 — The foundational beginner error of leaving every noun in its dictionary form, and how to retrain yourself to let the case ending carry the noun's role.
- stát — to stand; to costA2 — Full conjugation of the homonym stát (to stand / to cost), kept carefully apart from the separate perfective stát se (to happen / to become), which takes the instrumental.