〜たら — the universal conditional
Japanese has four conditionals (〜たら, 〜ば, 〜と, 〜なら), and Japanese learners spend a lot of pages worrying about which to pick. The shortcut: in everyday speech, 〜たら does almost all the work. Form: take the past form you met in lesson 18 (たべた, のんだ, 行った), tack on ら, and you've got 'if/when X happens, …'. 雨 が ふったら、行きません。 = 'If it rains, I won't go.' That's the sentence pattern of the day. We'll close with a brief look at 〜ば — useful in a few set phrases — and leave the rest of the conditional family for later.
Form: past form + ら
Take any verb's plain past (the た-form from yesterday) and add ら. たべた → たべたら ('if/when I eat'). のんだ → のんだら. 行った → 行ったら. 見た → 見たら. した → したら. 来た → 来たら. With い-adjectives, drop い and add かったら: さむい → さむかったら ('if it's cold'). With な-adjectives and nouns, use だったら: しずか だったら ('if it's quiet'), やすみ だったら ('if it's a day off'). One pattern, every word class.
If / when — both at once
〜たら covers two English meanings that often blur in real speech: the conditional 'if' and the temporal 'when (the trigger happens)'. 雨 が ふったら、行きません。 = 'If it rains, I won't go.' (uncertain). うち に かえったら、でんわ します。 = 'When I get home, I'll call you.' (definite — it's planned). Same pattern, both readings. The clue is whether the speaker treats the event as uncertain ('if') or as a future certainty ('when'). Japanese doesn't force you to pick one — context handles it.
Negative trigger — 〜なかったら
For 'if X doesn't happen', use the plain negative past — 〜なかった — and add ら: 〜なかったら. 時間 が なかったら、来なくて いい です。 = 'If there's no time, you don't have to come.' 雨 が ふらなかったら、こうえん に 行きましょう。 = 'If it doesn't rain, let's go to the park.' Pattern: drop the い of ない, add かったら. (You've already done this with regular adjectives — same move.)
Result clause — anything goes
The clause after 〜たら can be a statement, a suggestion (〜ましょう), a request (〜て ください), a command, a wish (〜たい) — Japanese doesn't restrict it the way some textbooks claim. 雨 が ふったら、タクシー で 行きましょう。 = 'If it rains, let's go by taxi.' しごと が おわったら、でんわ して ください。 = 'When work ends, please call me.' やすみ だったら、うみ に 行きたい です。 = 'If it's a day off, I want to go to the sea.' The trigger lives in 〜たら; the result is whatever you'd normally say.
A note on 〜ば — the formal cousin
〜ば is older and more formal. Full conjugation rules wait for B1; for now, just recognize a few set phrases that use it. もし よければ = 'if it's OK with you' — a soft, polite way to float a request. ぜひ いらして くだされば、うれしい です。 = 'If you'd come, I'd be delighted' (very formal). そう すれば いい。 = 'If you do that, it's fine.' Treat 〜ば as 'the polite/literary 〜たら' for now. In conversation, 〜たら does the same job and is what Japanese friends actually say.
Two cultural footnotes
(1) もし ('if', as a hedge) is often added at the start of an iffy conditional: もし 雨 が ふったら… = 'if (perhaps) it rains…'. It softens the guess. Optional but very common. (2) 〜たら どう です か = 'how about (doing) X?' is a gentle suggestion. すこし やすんだら どう です か。 = 'How about resting a little?' Useful for offering advice without sounding pushy.
