Relative Pronouns

The function of relative pronouns in English is usually served by “that,” “who” or “which.” In German the main ones are fully declined, and the relative clause is usually set off with commas:

Das Auto, das ich sah, war blau.
The car that I saw was blue.
Der Mann, der fuhr, hatte einen Hut auf.
The man who was driving had a hat on.

Note that “das” in the first sentence above is in the accusative case, as the car is the direct object of the verb “see” in the relative clause. The “der” in the second sentence is nominative, as the man is the subject of the relative clause.

As you may have noticed, the relative pronouns in German decline for the most part the same way as the definite article “the.” The only differences are in the dative plural and in the genitive:

Masculine Feminine Neuter Plural
Nominative der die das die
Accusative den die das die
Dative dem der dem denen
Genitive dessen deren dessen deren

Those genitive forms of the relative pronoun would usually translate to “whose” or "of which" in English. Since genitive constructions always involve two nouns – possessor and possessed – they can be a little tricky to decline. The relative pronoun takes its gender and number from the possessor:

Der Mann, dessen Hunde du hörst, ist mein Nachbar.
The man whose dogs you hear is my neighbor.