Lao is generally a subject–verb–object language, but emphasis can move the object to the beginning of a sentence. The language lacks both agreement and case marking, but word order is very free, with predicate-argument relations determined largely through context. Lao is a right-branching language, much like other Southeast Asian languages and, to a lesser extent, Romance languages.

Politeness

Since Lao culture is stratified based on the age, occupation, wealth or clout of the speaker, one must afford differing amounts of respect based on the discrepancy between one person and another. That affects language as well; to make language more polite, more formal language, including of pronouns (which can otherwise be dropped) and more formal versions of them, and sentence-ending particles can be used. Also, ending particles also serve to soften and make one's speech more polite.

• ແດ່ (dé [dɛ̄ː])

In addition to ending most general statements and the softening of imperatives and requests, it is also used to intensify the meaning (especially of adjectives and adverbs) more politely, to make the use of demonstrative pronouns more polite, or to indicate a certain amount or some extent of something.

• ເດີ (deu [dɤ̀ː]) or ເດີ້ (deu [dɤ̂ː]) or ເດ (dè [dèː])

They are used as a more intensive version of ແດ່, thus giving requests and demands more urgency and are used for statements that tend to be more emphatic. They are, therefore, not as polite. ເດ also has the sense of and what about or to indicate an equivalent to this as a demonstrative pronoun.

Nouns

Nouns are not marked for plurality, gender, or declension but may be single or plural. Unlike in English, nouns are not marked with articles. Measure words or classifiers (ລັກສະໜະນາມ, laksana naam [lāk sā.náʔ náːm]) are often used to express plurals, as classifiers must be used to count objects, but the noun itself remains unchanged.

Verbs of physical action are easily converted into nouns by adding ການ (kan [kàːn]) before the verb. Abstract actions and adjectives use ຄວາມ (khwam [kʰúam]) instead.

Pronouns

Pronouns (ສັບພະນາມ, sap pha nam [sáp pʰā.náːm]) are often dropped in informal contexts and replaced with nicknames or kinship terms, depending on the relation of the speaker spoken to (sometimes even spoken about). Pronouns can change based on register of speech, including the obsolete royal and the formal, informal and vulgar. In more formal language, pronouns are more often retained and more formal ones used. Pronouns can be pluralized by adding ພວກ (phuak [pʰûak]) in front: ພວກເຈົ້າ ([pʰûak.t͡ɕâw]) for "you plural". Age and status determine usage. Younger children's names are often prefixed with ບັກ (bak [bāk]) and ອີ (i [ʔìː]), respectively. Slightly older children are addressed to or have their names prefixed with ອ້າຍ (ai [ʔâːj]) and ເອື້ອຍ (èw-ai [ʔɯâj]), respectively, but ພີ່ (phi [pʰīː]) is also common. Much older people may be politely dressed as aunt, uncle, mother, father, or even grandmother or grandfather, depending on their age. In a company setting, one's title is often used.

Demonstrative pronouns

Verbs

Lao verbs (ກະລິຍາ, karigna [kā.lī ɲáː]) are not conjugated for tense, mood, or person. Tense is indicated by using time reference words, such as yesterday, next year, just now or by certain particles. Nouns that begin with ການ (kan [kàːn]) or ຄວາມ (khwam [kʰúam]), often nominalised verbs, become verbs again when those particles are dropped.

Copula

Lao has two forms of the verb to be, ເປັນ (pèn [pèn]) and ແມ່ນ (maen [mɛ̄n]) which are somewhat interchangeable. As a general rule, the latter is not used to describe people.

Tense

In a general, in a short Lao sentence, the verb is often not marked for tense and can be taken from context, with words such as yesterday, tomorrow, later, etc. If the subject of when the events occurred is already known, they can also be left out and inferred from dialogue. However, there are several ways to mark tense in Lao:

Past

The most common way to indicate a completed action is to end a statement with ແລ້ວ (lèw [lɛ̂ːw]). That can also be used to indicate events that occurred in the recent past. One can also use the particle ໄດ້ (dai [dâj]) preceding the verb, alone or in conjunction with ແລ້ວ, although this is less common and often used in negative statements and never for a continuous action.

Future

There are two markers used to indicate actions to be completed in the future, ຊິ (si [sī]) and ຈະ (cha [t͡ɕáʔ]). Both of these always precede the verb. To indicate that something is just about to happen, one can say ກຳລັງຈະ (kamlang cha [kàm.láŋ t͡ɕá]).

Progressive

Although no particle is generally needed to mark a present progressive statement, Lao uses three, ພວມ (phuam [pʰuám]) and ກຳລັງ (kamlang [kàm.láŋ]) before the verb, ຢູ່ (yu [jūː]) after it.

Modal verbs

Modal or auxiliary verbs (ວິກະຕິກະລິຍາ, vikatikaligna) are verbs that serve auxiliary function, such as want, obligation or need like English ought to, should, must, can, etc.

Obligation

ຄວນ (khouan [kʰuán]) Should, ought to

Need

ຕ້ອງ (tong [tɔ̂ŋ]) to need, must.
When the need is a noun, ຕ້ອງການ (tong kan [tɔ̂ŋ kàːn]) is used instead.

Want

ຢາກ, yak [jȁːk], to want, to desire
Used to express a want or desire. When this is a noun, then the form ຢາກໄດ້ (yak dai [jȁːk dâj]) or the common verb ເອົາ (ao [àw]) is used instead, but the latter is not as polite.

Can, be able to

ໄດ້ (dai [dâj]) to get, to have, to be able to
That is used to indicate the ability to do something. It is the closest Lao word for the English verb can and in requests when English speakers would use may. When used in that sense, it follows the verb; before the verb, the meaning changes to to get or to have.

ເປັນ (pèn [pèn]) to be, to be able to
In addition to being a verb for the copula, it can also be used to indicate that one can do something because of knowing how to do it.

ສາມາດ...ໄດ້ (samat...dai [sǎː mâːt ... dâj]) to be able to, to be possible
It functions much like can but with the sense of being physically possible to do.

Enter, join

ເຂົ້າ, khao [kʰȁw], to enter, to join, to participate
Used to indicate movement from one place to another inside, such as a house or building.

Recipiency

ໃຫ້, hai [hȁj] to give, to permit, to let
Used to indicate that the verb is intended for someone or something else or to express a desire, a wish, or a command.

Affirmation and negation

To say no is as simple as saying ບໍ່ (bo [bɔ̄ː]), and negation simply involves placing that word in front of the verb, adjective, adverb, or noun to be negated. To say yes, especially to indicate that one is listening, one uses ໂດຍ (doi [dòːj]), especially in formal situations, or ເຈົ້າ (chao [t͡ɕâw]). To answer a question, one often repeats the verb of action that was used in the question to indicate that that action was or will be completed. One can also use ແມ່ນ (mén [mɛ̄n]), especially if the question had ແມ່ນ, as an element of the interrogative particle.

Adverbs and adjectives

Little distinction can be made between adjectives and adverbs, as any adjective that could logically be used to modify a verb can also be used as an adverb. They are often duplicated to indicate a superlative and can even be modified like verbs, mainly by the lack of a copula to link the object and adjective/adverb. Adjectives come after the noun.

Equivalence, comparatives, and superlatives

To indicate that something is the same, one uses ຄືກັນ (khu kan [kʰɯ́ː kàn]). To indicate that one is similar to something else, one uses ຄືກັບ (khu kap [kʰɯ́ː káp]).

Comparatives take the form "A ກວ່າ (kwa [kuā]) B", or A is more than B. The superlative is expressed by "A ທີ່ສຸດ (thisut [tʰīː sút])", or A is the best. All adjectives can be altered in this way:

Questions

Lao uses special tag words at the beginning or the end of the sentence to indicate a question, so the modern use of the question mark (?) is redundant.

Yes–no questions end in ບໍ່ (bo [bɔ̄ː]), but Lao also has other sentence interrogative finals that indicate whether or not the speaker expects an answer, knows the answer to be expected, will be surprised, or is rhetorically asking a question, but they are generally used only in conversational settings.

Other common interrogatives
Who? ຜູ້ໃດ (phoudai [pʰȕː dàj]) and its common short form ໃຜ (phai [pʰǎj])

What? ຈັ່ງໃດ (changdai [t͡ɕāŋ.dàj]) and its common short form ຫຽັງ (gnang [ɲǎŋ])

Where? ໃສ (sai [săj])

When? ເມື່ອໃດ (mua dai [mɯ̄a dàj]), and many others.
There are numerous ways to ask when something will occur, many of which are formed by adding ໃດ (dai /dàj/) which after a noun marking time, e.g., ເວລາໃດ (vela dai [wéː láː dàj]), ຍາມໃດ (gnam dai [ɲáːm dàj]), and ປານໃດ (pan dai [pàːn dài]).

Why? ເປັນຈັ່ງໃດ (pen changdai [pèn t͡ɕāŋ.dàj])
The phrase by itself can also mean What's wrong?, but can also ask why or for what reason a condition is occurring.

How?
ແນວໃດ (nèw dai [nɛ́ːw dàj])
There are numerous ways to ask how?, some interchangeable with Lao equivalents for what? and why? but in the sense of how something is accomplished or done, one can also use ເຊັ່ນໃດ (sen dai [sēn.dàj]), ຢ່າງໃດ (yang dai [jāːŋ dàj]) or ດັ່ງໃດ (dang dai [dāŋ.dàj]).

How Much/Many? (General Things) ຈັກ (chak [t͡ɕák])

How Much? (Price) ເທົ່າໃດ (thao dai [tʰāw dàj]) or its variant ທໍ່ໃດ (tho dai [tʰɔ̄ː dàj])

Right? Correct? ແມ່ນບໍ່ (mèn bo [mɛ̄n bɔ̄ː])

Already? Yet? ແລ້ວບໍ່ (lèw bo /lɛ̂ːw bɔ̄ː/)

Or not? ຫຼືບໍ່ (lu bo /lɯ̀ bɔ̄ː/)

Eh? ຫຼື (lu /lɯ̀/)
This is a rather informal interrogative particle equivalent to English eh? or hmm? or huh?.

Answers to questions usually just involve repetition of the verb and any nouns for clarification.

• Question: ສະບາຍດີບໍ່ (sabai di bo [sā.bàːj dìː bɔ̄ː]) Are you well?
• Response: ສະບາຍດີ (sabai di [sā.bàːj dìː]) I am well or ບໍ່ສະບາຍ (bo sabai [bɔ̄ː sā.bàːj]) I am not well.

Words asked with a negative can be confusing and should be avoided. The response, even without the negation, will still be negated by the nature of the question.

• ບໍ່ສະບາຍບໍ່ (bo sabai di bo /bɔː sa.baj diː bɔː/) Are you not well?
• Response: ບໍ່ສະບາຍ (bo sabai di /bɔː sa.baj diː/) I am well.

Classifiers

Classifiers (ລັກສະນະນາມ, laksananam /lāk sā.nāʔ.náːm/) are used for when referring to a number of things, either a group or a finite amount. Classifiers can be used in place of the counted noun when context makes it sufficient. There are many classifiers, which is daunting, and it is better to double the noun or the more common ones such as ທີ່ (thi /tʰīː/) or ໂຕ (to /toː/). For single items, the classifier comes before the number; for more, the classifier comes after it.

The classifiers can sometimes be used in place of the nouns they group in context.

Possession

To indicate that object X belongs to object Y, Lao uses the construction X ຂອງ Y. ຂອງ (khong /kʰɔ̌ːŋ/) can also be omitted without changing the meaning.