Mostly in 2 cases: - When you say how someone feel about someone else's action. ex : I would like you to come = je voudrais que tu viennes (venir in subjonctif) ex : He's happy that you are here = il est content que tu sois là. (être in subjonctif) - When using "il faut que" (I need to) - this phrase is used a lot- ex : Il faut que je parte dans 5 minutes. (partir in subjonctif) Notice that there is always a "que" in fornt of each subject, so if you happen to make a sentence with "that I..." then it should be followed by subjonctif.