The Past Perfect Subjunctive in Swedish grammar is a verb form used to describe actions that might have been completed in the past, given certain conditions. It is often used in dependent clauses following conjunctions that express doubt, uncertainty, or hypothetical situations. In Swedish, the Past Perfect Subjunctive is formed by using the auxiliary verb “hade” with the past participle of the main verb. Mastering the Past Perfect Subjunctive is essential for accurately expressing complex ideas and hypothetical situations in Swedish.