Interrogative Pronouns: wer and was

To ask "who?" and "what?" in German, you use wer and was. They look like simple one-to-one translations of the English words, but there is a twist that trips up almost every English speaker: wer changes its form depending on its grammatical role in the sentence, while was stays the same and refuses to stand next to a preposition. This page walks through both, and once you understand why they behave differently, you will never have to guess.

wer asks about people and declines for case

Wer means "who" and always refers to people (or, occasionally, to a thing whose identity is in question, as in "Wer hat das gemalt?" — "Who painted this?"). The key fact is that wer is a case-marked pronoun: it carries a different ending depending on whether the person you are asking about is the subject, the direct object, the indirect object, or a possessor.

English used to do this too — that is exactly the old distinction between who (subject) and whom (object). Modern English has nearly buried whom, so most speakers say "Who did you see?" without a second thought. German keeps the full system alive and obligatory. You cannot use the nominative wer for an object; that is a genuine grammatical error, not just a stylistic slip.

Here is the complete paradigm:

Notice how cleanly the endings mirror the masculine definite article: der → wer, den → wen, dem → wem, dessen → wessen. If you already know your case endings, wer comes almost for free.

wer (nominative) — the subject

Use wer when the person you are asking about is doing the action.

wen (accusative) — the direct object

Use wen when the person is on the receiving end of the verb — the one being seen, called, invited, asked.

wem (dative) — the indirect object

Use wem for the person who benefits from or is affected by the action — the one you give something to, help, thank, or answer.

Dative also follows the dative prepositions, so "with whom," "to whom," "from whom" all use wem:

wessen (genitive) — the possessor

Use wessen to ask "whose." It comes directly before the noun it modifies, and that noun loses its article — exactly as in English "whose car," not "whose the car."

Wessen is fully standard but sounds a touch formal in casual speech; in very relaxed conversation many native speakers reach for the dative-based phrasing "Wem gehört...?" ("Who does ... belong to?") instead. Both are correct — wessen is just more compact.

was asks about things and (almost) never declines

Was means "what" and refers to things, actions, abstractions, and unidentified entities. Unlike wer, it has essentially one form. It serves as both the subject and the direct object with no change at all.

In the first sentence was is the subject; in the second it is the direct object. Same word both times. This is one of the rare places where German is simpler than the wer-system suggests.

There is a genitive form, wessen (yes, the same word as for people), but asking "of what" is so rare in modern German that you can safely ignore it until an advanced level. There is no dative form of was at all — and that gap is the source of the most important rule on this page.

The big trap: no "preposition + was" — use wo-compounds

Here is the rule that separates learners who sound native from those who don't. In standard German, you cannot put a preposition in front of was. You do not say mit was, für was, auf was, über was. Instead, the preposition fuses onto the front of the word wo (with an extra -r- when the preposition starts with a vowel):

The -r- appears purely for pronunciation, to keep two vowels from colliding: wo + auf would be the awkward "wo-auf," so it becomes worauf. Compare womit (consonant, no -r-) with worauf (vowel, -r- inserted).

The same logic explains why people use wem with prepositions but never was: a person fits into the dative and so takes a real preposition (mit wem — "with whom"), whereas a thing has no dative form and must escape into a wo-compound (womit — "with what").

Why German bothers with all this

The deep reason wer declines and was doesn't is that German marks grammatical role with case endings rather than with word order. English signals "who is doing what to whom" mainly through position: The dog bit the man versus The man bit the dog. German lets word order flex, so it needs the case ending on the question word itself to tell you what is being asked. That is why Wen siehst du? is unambiguous even though the object comes first — the -n on wen announces "this is the object" before you even reach the verb.

Common Mistakes

English speakers make a predictable set of errors here, almost all caused by English having merged who/whom and by English freely allowing "preposition + what."

Key Takeaways

• wer = who (people), and it declines: wer / wen / wem / wessen for nominative / accusative / dative / genitive. The endings echo the masculine article der / den / dem / dessen.
• was = what (things), and it stays the same for subject and object. Its genitive is rarely needed and it has no dative.
• You can never write preposition + was. Replace it with a wo-compound: womit, wofür, worauf, worüber (insert -r- before a vowel).
• People keep their prepositions (mit wem, für wen); things switch to wo-compounds (womit, wofür).