Which French conjunctions always take the subjunctive?

A fixed list: bien que and quoique (although), pour que and afin que (so that), avant que (before), jusqu'à ce que (until), à condition que and pourvu que (provided that), sans que (without), de peur que and de crainte que (for fear that), and à moins que (unless). Every one of them forces the subjunctive on the verb in the clause it introduces, with no exceptions to judge: bien qu'il soit tard (although it is late), je reste jusqu'à ce qu'elle revienne (I am staying until she comes back). Because it is a closed list, the safest strategy is simply to memorise it.

What is the ne explétif and when do you use it?

The ne explétif is a ne that appears after certain conjunctions and verbs without making the sentence negative - it is a stylistic leftover, not a real negation. It turns up optionally after avant que, à moins que, de peur que and de crainte que: avant qu'il ne parte (before he leaves), à moins qu'il ne pleuve (unless it rains). It carries no negative meaning, takes no pas, and you can leave it out in everyday French. It is worth recognising for reading and worth using to sound polished in formal writing, but it never changes the meaning.

Why does après que take the indicative when avant que takes the subjunctive?

Because avant que (before) points at an event that has not yet happened - it is still hypothetical when you speak - so French marks it with the subjunctive. après que (after) points at an event that has actually taken place; it is real and completed, so traditionally it takes the indicative: après qu'il est parti (after he left). In modern usage many French speakers wrongly extend the subjunctive to après que by analogy with avant que, but the textbook and exam answer keeps après que in the indicative.

The French Subjunctive After Conjunctions

If you have learned to build the present subjunctive on the formation page and met the triggers of necessity and will and doubt and emotion, this page covers the most mechanical triggers of all: conjunctions. Unlike opinion verbs, where you have to weigh whether a clause is asserted or doubted, conjunctions are a fixed list. If the conjunction is on the list, the verb goes subjunctive. Full stop.

That makes this the easiest part of the subjunctive to score on in an exam, provided you have memorised the list. The underlying logic is the familiar one - these conjunctions all introduce something not yet real: a purpose not yet achieved, a condition not yet met, an event not yet reached - but you do not even need the logic. You need the list.

The always-subjunctive conjunctions

Every conjunction below forces the subjunctive on the verb in its clause:

bien que / quoique (although): Bien qu'il soit tard, je reste. (Although it is late, I am staying.)
pour que / afin que (so that): Je t'aide pour que tu réussisses. (I am helping you so that you succeed.)
avant que (before): Partons avant qu'il ne pleuve. (Let us leave before it rains.)
jusqu'à ce que (until): Attends jusqu'à ce qu'elle revienne. (Wait until she comes back.)
à condition que / pourvu que (provided that): Tu peux sortir à condition que tu finisses tes devoirs. (You can go out provided you finish your homework.)
sans que (without): Il est parti sans que nous le sachions. (He left without our knowing.)
de peur que / de crainte que (for fear that): Je ferme la porte de peur qu'il n'entre. (I am shutting the door for fear he comes in.)
à moins que (unless): Nous viendrons à moins qu'il ne fasse trop froid. (We will come unless it is too cold.)

Conjunction	Meaning	Example
bien que / quoique	although	bien qu'il soit fatigué
pour que / afin que	so that	afin que vous compreniez
avant que	before	avant que tu partes
jusqu'à ce que	until	jusqu'à ce qu'il finisse
à condition que	provided that	à condition que nous soyons à l'heure
pourvu que	provided that	pourvu qu'elle vienne
sans que	without	sans que je le veuille
de peur que	for fear that	de peur qu'il ne tombe
à moins que	unless	à moins que tu aies une meilleure idée

The ne explétif

A handful of these conjunctions take an optional ne explétif - a ne that looks like a negation but is not one. It carries no negative meaning, takes no pas, and the sentence stays positive:

Partons avant qu'il ne parte. (Let us leave before he leaves.)
Nous viendrons à moins qu'il ne pleuve. (We will come unless it rains.)
Je le préviens de peur qu'il ne soit en retard. (I am warning him for fear he will be late.)

It appears after avant que, à moins que, de peur que and de crainte que. You can drop it entirely in everyday French and the meaning is identical - avant qu'il parte is just as correct. Recognise it when reading, and use it to sound polished in formal writing, but never read it as a negative.

après que takes the indicative

The mirror of avant que is the classic trap. avant que (before) points at an event that has not yet happened when you speak, so it is hypothetical and takes the subjunctive. après que (after) points at an event that has already happened - it is real and completed - so it traditionally takes the indicative:

avant que -> subjunctive: avant qu'il parte (before he leaves).
après que -> indicative: après qu'il est parti (after he left).

In modern speech many French speakers wrongly extend the subjunctive to après que by analogy with avant que, and you will hear "après qu'il soit parti" in the wild. The exam and textbook answer keeps après que in the indicative.

While you are sorting out the "so that" idea, keep the purpose versus result distinction tight: pour que and afin que express purpose - an aim not yet achieved - and take the subjunctive (je parle lentement pour que tu comprennes, I speak slowly so that you understand). A genuine result that has actually happened uses si bien que (so that / with the result that) and stays in the indicative (il a parlé lentement, si bien que tout le monde a compris, he spoke slowly, so that everyone understood).

The same-subject shortcut

Several of these conjunctions have an infinitive form used when both halves of the sentence share the same subject. Just like the different-subject rule on the necessity and emotion pages, French refuses the que clause when there is only one subject and switches to an infinitive instead:

pour que -> pour + infinitive: Je travaille pour réussir. (I work in order to succeed.) - I work, I succeed: one subject, infinitive. Contrast Je travaille pour que tu réussisses. (I work so that you succeed.) - two subjects, subjunctive.
avant que -> avant de + infinitive: Je réfléchis avant de parler. (I think before speaking.) - one subject. Contrast Je réfléchis avant que tu parles. (I think before you speak.) - two subjects.
afin que -> afin de + infinitive: afin de réussir versus afin que tu réussisses.
à condition que -> à condition de + infinitive: à condition de finir versus à condition que tu finisses.
de peur que -> de peur de + infinitive: de peur de tomber versus de peur qu'il ne tombe.

A few conjunctions have no infinitive shortcut and always keep the subjunctive even with the same subject - bien que, quoique, jusqu'à ce que and pourvu que among them. For those, the que clause and subjunctive stay put regardless of the subjects.

Worked examples

Bien qu'il fasse froid, nous sortons. (Although it is cold, we are going out.) - bien que + irregular faire.
Je te le dis afin que tu sois prêt. (I am telling you so that you are ready.) - afin que + irregular être.
Reste ici jusqu'à ce que je revienne. (Stay here until I come back.) - jusqu'à ce que + revenir.
Tu réussiras pourvu que tu travailles. (You will succeed provided you work.) - pourvu que + travailler.
Il est sorti sans que personne le voie. (He went out without anyone seeing him.) - sans que + irregular voir.
Nous partirons à moins qu'il ne fasse trop chaud. (We will leave unless it is too hot.) - à moins que + ne explétif + faire.
Je travaille pour réussir. (I work in order to succeed.) - same subject, so pour + infinitive, no subjunctive.
Après qu'il est arrivé, nous avons mangé. (After he arrived, we ate.) - après que + indicative.

Common mistakes English speakers make

The most common slip is using a que clause with a subjunctive when both subjects are the same - "je travaille pour que je réussisse" is wrong; one subject means je travaille pour réussir. The same goes for avant que: "avant que je parte" with the speaker on both sides should be avant de partir. A second error is reading the ne explétif as a negation and adding pas - "avant qu'il ne parte pas" reverses the meaning; the bare ne is not negative. A third is extending the subjunctive to après que - the textbook answer is the indicative, après qu'il est parti. Learners also forget that a small set of conjunctions (bien que, quoique, jusqu'à ce que, pourvu que) keep the subjunctive even with one subject, because they have no infinitive shortcut. Finally, do not confuse purpose with result: pour que (purpose, subjunctive) is not si bien que (result, indicative).