Past Tense of “lay”
The past tense of lay is laid; the past participle is laid.
Why “lay” behaves this way
"Lay" descends from Old English "lecgan," a causative verb built directly from an older grade of the vowel found in "licgan" (the ancestor of "lie," to recline) — in other words, "lay" was constructed in Old English specifically to mean "to cause [something] to lie down," making it a deliberate causative partner to "lie" rather than a coincidentally similar word. That causative relationship, "lie" (to recline yourself) versus "lay" (to place something else down), is still exactly how the two verbs function today, even though centuries of sound change and everyday confusion have blurred the line between them for most modern speakers.
The confusion between "lay" and "lie" is compounded by the fact that "lay" is also, coincidentally, the simple past tense of the historically related but grammatically separate verb "lie" — so "I lay down yesterday" (past tense of "lie," to recline) and "I lay the book down" (present tense of "lay," to place something) look identical on the page despite belonging to two different verbs in two different tenses, a genuine structural collision that has confused English speakers for centuries, not merely a modern error.
The common confusion
The core confusion is that "lay" always requires a direct object (you lay something down) while "lie" never takes one (you simply lie down yourself) — and because "lay" also happens to be the simple past tense of "lie," a sentence like "I lay down for a nap" is correct past-tense "lie," not present-tense "lay," which trips up even careful native speakers constantly.
How it's actually used
"Lay" appears in a wide range of fixed collocations detached from its literal placing sense — "lay blame," "lay a trap," "lay claim to," "lay eyes on" — all of which still require a direct object, consistent with its transitive core meaning, unlike the intransitive "lie," which never takes one in any of its idioms either ("lie in wait," "lie low"). Poultry farming and biology also use "lay" in its most literal original sense (a hen lays eggs), a usage that has stayed remarkably stable and unambiguous compared to the recline/place confusion elsewhere. Geology and construction also use "lay" in specialized senses — "lay a cable," "lay track," "lay a foundation" — all transitive, all consistent with the verb's causative core meaning of placing or positioning something with deliberate care.
Across the tense system
Across tenses, "lay" (transitive) and "lie" (intransitive) keep parallel but distinct conjugations — lay/laid/laid versus lie/lay/lain — meaning the past tense of "lie" and the present tense of "lay" collide in spelling only, never in the full paradigm, which is why checking the participle ("has laid" versus "has lain") is often the clearest way to identify which verb a confusing sentence is actually using.
Common real mistakes
By far the most common real error in English is using "lay" where "lie" is grammatically required — "I'm going to lay down" instead of the correct "I'm going to lie down" — an error so widespread in casual speech that it's steadily eroding the distinction in everyday usage, even though careful formal writing still enforces it strictly. The reverse error, using "lie" transitively with an object ("lie the book on the table" instead of "lay the book on the table"), is rarer but does occur, usually among writers overcorrecting once they've learned the lay/lie rule exists.
Examples
- She laid the blanket over the sleeping baby.
- He has laid out his plans for the project.
- They laid the foundation before winter set in.
- We had laid everything out on the table already.
- The hen lays an egg almost every day.
- Lay your cards on the table.
- The town lay quiet in the early morning. (past tense of 'lie')
- She's laying the groundwork for a career change.
Memory trick
Test with an object: if you can insert "it" or "something" right after the verb and the sentence still makes sense ("lay it down"), you want "lay." If the sentence is only about a person or thing existing in a reclining position with nothing being placed ("I lie down"), you want "lie" — and remember "lay" doing double duty as the past tense of "lie" is the real source of the tangle, not a sign you're doing it wrong.