The French causative construction describes an action that is being caused—rather than performed—by the subject of the sentence: he/she/it is causing something to happen, having something done, or making someone do something. A causative sentence must have a subject (which may be a person or thing), the conjugated verb faire, and the infinitive of another verb, as well as at least one of these two things: a "receiver" (a person or thing being acted upon) and/or an "agent" (a person or thing being made to act).
1. Receiver only
The subject of the sentence makes something happen to the receiver:
subject + faire + infinitive + receiver
Je fais laver la voiture.
I'm having the car washed.
Il fait réparer la machine.
He's having the machine repaired.
Vas-tu faire désherber le jardin ?
Are you going to have the garden weeded?
J'ai fait faire un gâteau.
I had a cake made.
2. Agent only
The subject makes the agent do something:
subject + faire + infinitive + agent
Note that there is no preposition.*
Je fais écrire David.
I'm making David write.
Il fait manger sa sœur.
He makes his sister eat.
Les orages font pleurer mes enfants.
Storms make my children cry.
J'ai fait cuisiner André.
I had/made André cook.
3. Receiver + Agent:
The subject has the agent do something to the receiver:
subject + faire + infinitive + receiver + par or à* + agent
Je fais laver la voiture par/à David.
I'm having David wash the car.
Il fait réparer la machine par/à sa sœur.
He's having his sister fix the machine.
Je vais faire faire un gâteau par/à André.
I'm going to have André make a cake.
(It might look strange, but faire faire is correct; Je
vais faire un gâteau would mean "I'm going to make a cake" - see page 3.)
Vas-tu faire examiner les enfants par le/au médecin ?
Are you going to have the doctor examine the kids?
*Note that the agent is preceded by a preposition only when there is also a receiver; this is particularly important when they are both people, as in the final example, because it lets you know which is which. Also see "object pronouns" on page 3.
A rare example of the causative without agent or receiver (though the latter is obvious from whatever the other person is holding) is Fais voir.
Page 1 - Faire + infinitive
Page 2 - Se faire + infinitive
Page 3 - Causative with objects and agreement