Subordinating conjunctions link a subordinate clause to a main clause and mark the logical connection that unites them. They introduce ideas of time, cause, purpose, consequence, concession, condition or complementation. They are essential for building complex sentences and for guiding the choice of mood in Propositions et Subordonnées.

When, whenever and as soon as introduce a temporal relation between two actions. They place the subordinate clause in the time of the main clause without changing the lexical meaning of the verb. In this group, the subordinate clause most often follows the main clause, but it can also precede it with a comma.

RègleRule	ExempleExample
Quand marque la simultanéité ou l’habitude.When marks simultaneity or habit.	Quand j’arrive, il part.When I arrive, he leaves.
Lorsque est plus soutenu que quand.Lorsque is more formal than quand.	Lorsque le soleil se couche, la ville se calme.When the sun sets, the city quiets down.
Dès que exprime la succession immédiate.As soon as expresses immediate succession.	Dès qu’elle finit, elle appelle sa mère.As soon as she finishes, she calls her mother.

Parce que, puisque and comme introduce a cause and answer the question why. Parce que is the most neutral, since it presents a cause admitted or evident, and comme is often placed at the start of the sentence. The literary register also uses car, which remains coordinating and does not change the mood of the clause.

RègleRule	ExempleExample
Parce que présente la cause la plus courante.Parce que presents the most common cause.	Il reste chez lui parce qu’il est malade.He stays at home because he is sick.
Puisque renvoie à une cause considérée comme connue.Puisque refers to a cause considered as known.	Puisque tu es prêt, nous pouvons partir.Since you are ready, we can leave.
Comme s’emploie souvent au début de la phrase.Comme is often used at the beginning of the sentence.	Comme il pleuvait, nous sommes rentrés.As it was raining, we went back home.

Pour que and afin que express the goal pursued by the action of the main clause. They require the subjunctive because the goal is regarded as desired but not yet realized. Their subordinate clause can appear before or after the main clause depending on the sentence organization.

RègleRule	ExempleExample
Pour que introduit un but concret.Pour que introduces a concrete goal.	Je parle lentement pour que tout le monde comprenne.I speak slowly so that everyone understands.
Afin que est plus soutenu que pour que.Afin que is more formal than pour que.	Il ferme la porte afin que personne n’entende.He closes the door so that no one hears.
Le verbe de la subordonnée se met au subjonctif.The verb in the subordinate clause is in the subjunctive.	Nous travaillons pour que tu sois satisfait.We are working so that you are satisfied.

Si bien que and de sorte que introduce the consequence of a fact presented as real. They generally require the indicative, since the consequence is seen as a given. They can also link two clauses very closely without changing the logical meaning of the sentence.

RègleRule	ExempleExample
Si bien que marque une conséquence effective.Si bien que marks an actual consequence.	Il a beaucoup neigé si bien que les routes sont fermées.It snowed heavily, so the roads are closed.
De sorte que présente le résultat d’une action.De sorte que presents the result of an action.	Elle a parlé clairement de sorte que tout le monde a compris.She spoke clearly so that everyone understood.
L’indicatif convient quand le résultat est affirmé.The indicative is appropriate when the result is stated.	Il a étudié, de sorte qu’il a réussi.He studied, so that he passed.

Bien que, quoique and malgré que express a concession, that is, an idea opposite to what would be expected. They require the subjunctive in standard usage. This type of linkage is common in a polished register and allows opposing two facts without canceling the first.

RègleRule	ExempleExample
Bien que introduit une opposition réelle mais incomplète.Bien que introduces a real but incomplete opposition.	Bien qu’il soit fatigué, il continue.Although he is tired, he continues.
Quoique est synonyme de bien que et plus littéraire.Quoique is synonymous with bien que and more literary.	Quoique le temps soit court, nous attendons.Although time is short, we wait.
Malgré que est possible dans certains usages soignés.Malgré que is possible in some refined usages.	Malgré qu’il soit tard, ils travaillent encore.Although it is late, they are still working.

Si introduces a condition and is built with the indicative in most cases. À condition que expresses a necessary condition and requires the subjunctive. The conditional subordinate clause can precede or follow the main clause, which mainly affects the rhythm of the sentence.

RègleRule	ExempleExample
Si présente une condition ordinaire.If presents an ordinary condition.	Si tu viens, nous dînerons ensemble.If you come, we will dine together.
À condition que marque une condition stricte.À condition que marks a strict condition.	Tu réussiras à condition que tu travailles régulièrement.You will succeed provided you work regularly.
La subordonnée conditionnelle peut ouvrir la phrase.The conditional subordinate clause can open the sentence.	Si elle accepte, nous commencerons demain.If she agrees, we will start tomorrow.

Comme and ainsi que can link two clauses in a relation of comparison or addition. Their value depends on the context, because comme can also introduce a cause and ainsi que can mark accompaniment or addition. The correct reading therefore depends on the place in the sentence and the overall meaning.

RègleRule	ExempleExample
Comme peut exprimer une comparaison ou une ressemblance.Comme can express a comparison or resemblance.	Il chante comme son frère chante.He sings as his brother sings.
Ainsi que ajoute un élément à un autre.Ainsi que adds an element to another.	Elle parle français ainsi que l’espagnol.She speaks French as well as Spanish.
Le contexte détermine la valeur exacte.The context determines the exact value.	Comme il est prudent, il avance lentement.As he is prudent, he proceeds slowly.

Que often introduces a complement clause that depends on a verb, an adjective or an impersonal construction. The mood of the subordinate clause depends on the governing verb, which explains the alternation between indicative and subjunctive. This structure is central to the syntax of Propositions et Subordonnées.

RègleRule	ExempleExample
Que introduit souvent une proposition objet.Que introduces often an object clause.	Je pense qu’il vient.I think that he is coming.
Le mode dépend du verbe principal.The mood depends on the main verb.	Je souhaite qu’il vienne.I wish that he would come.
Le verbe régissant commande la subordonnée.The governing verb commands the subordinate clause.	Il faut que nous soyons prêts.It is necessary that we be ready.

Avant que indicates that a fact must occur before another and requires the subjunctive. Après que indicates a later, accomplished fact and requires the indicative in prescriptive usage. In spoken language, the subjunctive sometimes appears after après que, but the written norm keeps the indicative.

RègleRule	ExempleExample
Avant que demande le subjonctif.Avant que requires the subjunctive.	Pars avant qu’il ne fasse nuit.Leave before it gets dark.
Après que demande l’indicatif.Après que requires the indicative.	Après qu’il est parti, nous avons fermé la maison.After he left, we closed the house.
L’usage oral peut varier après après que.In spoken use, the subjunctive may appear after après que.	Après qu’il soit parti, ils ont appelé.After he left, they called.

The sequence of tenses governs the choice of tense in the subordinate clause according to the tense of the main clause. It organizes simultaneity, anteriority or posteriority without being limited to a single conjunction. A comma may separate the main clause and the subordinate clause when the sentence structure makes it clearer or more rhythmic.

RègleRule	ExempleExample
Le temps de la subordonnée dépend de la principale.The tense of the subordinate depends on the main clause.	Il disait qu’il viendrait.He said that he would come.
La relation temporelle guide le choix du temps.The temporal relation guides the choice of tense.	Quand il arriva, tout le monde se tut.When he arrived, everyone fell silent.
Une virgule peut marquer la frontière syntaxique.A comma can mark the syntactic boundary.	Comme il pleuvait, nous sommes restés.Since it was raining, we stayed.

These conjunctions structure the logical links between the clauses and guide the choice of mood or tense. Some introduce a factual statement, others an intention, an opposition or a condition, which explains the alternation between indicative and subjunctive. Mastery of them is essential to read, understand and produce complex sentences in Conjunctions and in Propositions and Subordinate Clauses.