między + Accusative

In Polish, prepositions of place often change their case based on whether they describe a state or a movement. The synonym pomiędzy can be used interchangeably with między for emphasis.

Motion vs. State Comparison:

• Motion (Accusative): Idę między drzewa. (I am walking into the space between the trees.)
• State (Instrumental): Stoję między drzewami. (I am standing between the trees.)

1. Directional Movement: When the phrase specifies a destination reached, as with iść (to go), włożyć (to put in), or upaść (to fall), 'między' governs the accusative case. This answers the question Dokąd? (To where?).

2. Connecting Objects: When describing movement between two specific objects (X and Y), the conjunction a is often preferred for clarity (e.g., między stół a krzesło). However, i is also acceptable and remains the standard choice when referring to a set or a general distribution.

3. Case Endings:

• Feminine Singular: Most end in -ę (e.g., książkę), but those ending in a consonant are identical to the Nominative (e.g., noc).
• Neuter Singular: Identical to the Nominative (e.g., okno).
• Masculine Inanimate Singular: Identical to the Nominative (e.g., stół).
• Masculine Animate/Personal Singular: Identical to the Genitive, ending in -a (e.g., brata, psa).
• Masculine Personal Plural: Identical to the Genitive (ends in -ów or -y/-i).
• Other Plurals: Identical to the Nominative (e.g., książki, drzewa).

4. Abstract Division vs. Choice: This pattern is used for abstract concepts of division (e.g., dzielić czas między pracę i dom). Note that prescriptive Polish grammar strictly requires the conjunction i (not a) when indicating the targets of division. Conversely, choosing between alternatives (wybierać między) uses the instrumental case instead.

5. Time Expressions: When między is used for time (e.g., 'between Monday and Wednesday'), it describes a location in time and always takes the instrumental case, never the accusative (e.g., między poniedziałkiem a środą).

6. Modern Usage: In casual speech, many Poles use the instrumental case even for movement. However, using the accusative is considered the correct standard in formal writing and exams.

Pronouns and Less Obvious Endings: A destination or distribution uses accusative pronouns: Wejdź między nas (Come in among us), Podziel to między mnie i niego (Divide it between me and him). After the preposition, the third-person pronoun has n-: niego, nią, nich. Contrast locative relation między nami (between us, instrumental). The feminine noun pani has accusative panią; masculine-personal plural mężczyzn has no overt ending: Wszedł między mężczyzn (He went in among the men).

Wybierać itself does not always require instrumental: Wybieram książkę (I am choosing a book) has an accusative object. It is the construction wybieram między książką a filmem that uses instrumental after między.