• Adjectives add more descriptive information to nouns. They are called modifiers because they modify (or change) the image in your mind. Consider:


    brown dog

    little brown dog

    little brown wiener dog


    With each adjective added, the picture in your mind changes to something more specific.

    Adjective clauses are a group of words containing both a noun and a verb that work as adjectives. They always follow the word being described and must begin with one of the following words: who, whose, which, where, or that.

    Because they must begin with one of five words, adjective clauses are easy to spot and write. And, because you are a native speaker, you will instinctively follow each of those words with a verb.



    In a sentence, target a noun that could use more descriptive information. Depending on that noun, use one of the five beginning words. If the noun is a person, use WHO. If the noun is a thing, use WHICH. If the noun is a place, use WHERE. To show ownership, begin with WHOSE. See the discussion below about using THAT.


    The ancient sea captain strolled along the deck.

    The ancient sea captain, whose brilliant grey eyes shone like two pearls on his darkly weathered face, strolled along the deck, where his crew lolled about in the hot Caribbean sun.


    The cow munched on grass.

    The cow that Jimmy planned to enter in the 4-H competition munched on grass, which glistened in the morning sun.


    The teacher entered the lunchroom.

    The teacher, who rarely ventured from the papers stacked on her desk, entered the lunchroom, which bustled with the usual mid-day chaos.


    Review: Adjective clauses must begin with one of the following five words: who, which, whose, that, or where. Target a noun in a sentence that can be more descriptive. Immediately follow the noun with an appropriate word that begins an adjective clause. Then simply finish out the thought with appropriate details.



    Commas separate what is essential from what is nonessential. The essential part of the sentence is the main idea. Think of the main idea as the base sentence to which we add additional information. Anything "extra," that doesn't have to be there, is set off by commas.

    Most adjective clauses are set off by commas; however, sometimes we need the information in the adjective clause. These necessary adjective clauses change the meaning of the sentence if taken away. Consider:

    The boy who rode his bicycle to school arrived late. (If you remove the adjective clause from this sentence, you are left with "The boy arrived late"--a different idea than that intended.) 

    The film that starred Charlton Heston won an academy award. (If you remove the adjective clause from this sentence, you are left with "The film won an academy award"--a different idea than that intended.) 

    In cases where the adjective clause is necessary to the basic meaning of the sentence, no commas should be used. If the information can be dropped without changing the basic meaning of the sentence, then use commas.

    Here is an example from above:

    The cow that Jimmy planned to enter in the 4-H competition munched on grass, which glistened in the morning sun.

    --Note how the first adjective clause makes it necessarily clear which cow the speaker is writing about. It is necessary to the meaning of the sentence; hence, no commas. But the second adjective clause adds only descriptive value. It doesn't touch on the main idea; thus, commas separate it from the base sentence.



    Perhaps the most difficult matter with adjective clauses is determining whether to use "which" or "that." Often, the choice does not matter. Either could be used. But occasionally, it does matter. Please consider the following:

    Source: http://grammar.ccc.commnet.edu/GRAMMAR/notorious/that.htm

    "The word which can be used to introduce both restrictive and nonrestrictive clauses, although many writers use it exclusively to introduce nonrestrictive clauses; the word that can be used to introduce only restrictive clauses. Think of the difference between

    • "The garage that my uncle built is falling down."
    • "The garage, which my uncle built, is falling down."

    I can say the first sentence anywhere and the listener will know exactly which garage I'm talking about — the one my uncle built. The second sentence, however, I would have to utter, say, in my back yard, while I'm pointing to the dilapidated garage. In other words, the "that clause" has introduced information that you need or you wouldn't know what garage I'm talking about (so you don't need/can't have commas); the "which clause" has introduced nonessential, "added" information (so you do need the commas)."

    In the above analysis, the speaker uses the word "restrictive" clause. In grammar, "restrict" basically means to "limit." Here are additional examples and a different explanation from another source:

    From: http://www.getitwriteonline.com/archive/103103.htm

    1. Our house [that has a red door and green shutters] needs painting.
    2. Our house, [which has a red door and green shutters], needs painting.
    3. The classrooms [that were painted over the summer] are bright and cheerful.
    4. The classrooms, [which were painted over the summer], are bright and cheerful.

    In all four cases, the adjective clause tells us something about either the house or the classrooms, but the choice of which or that changes the way we should read each sentence.

    In the first sentence, the use of that suggests that we own more than one house and therefore must explain to you that we are talking about a particular house of ours--the one with a red door and green shutters. We cannot leave out that adjective clause because it is essential to your understanding of the sentence; that is, you wouldn't know which one of our houses needs the paint job without that adjective clause.

    The second sentence tells you that we own only one house and we are simply telling you--in case you want to know--that it happens to have a red door and green shutters. We could leave out the information in that adjective clause and the sentence would still make sense.

    The third sentence, because it uses that to launch its adjective clause, tells us that only SOME of the classrooms were painted over the summer. If we omitted the clause "that were painted over the summer," we would be left with "The classrooms are bright and cheerful," a statement that would not be accurate since it would imply that ALL the classrooms are bright and cheerful. In this sentence, therefore, the adjective clause is essential to the meaning of the sentence.

    We call the adjective clauses in sentences one and three restrictive because they restrict--or limit--the meaning of the nouns they modify. In the case of sentence three, they tell us that we are talking ONLY about the classrooms that were painted over the summer--not the others.

    The which clause in the fourth sentence is what we call a nonessential--or nonrestrictive--clause. Since that sentence intends to tell us that ALL the classrooms were painted, the information in the adjective clause is not essential. The sentence would be clear even if the clause were omitted.

    The rule of thumb, then, is that which clauses are nonrestrictive (nonessential) while that clauses are restrictive (essential). Nonrestrictive clauses and phrases are set off from the rest of a sentence by a pair of commas (as in our examples above) or by a single comma if they come at the end of the sentence. (Example: "I took a vacation day on my birthday, which happened to fall on a Monday this year.")


    Please see the link at the bottom of this page for a lengthier discussion, with examples, about whether to use "which" or "that" to begin an adjective clause.