Parallelism may not appear evident in this verse. However, it is the dependence of line b on line a to complete its sense that makes the second line parallel to the first. In some languages this dependence will have to be more explicitly stated.

Yahweh is often spoken of as the shepherd of Israel (see 28.9; 77.20; 78.52; and especially Ezek 34.11-16). In many languages where domestic animals such as sheep, camels, or llamas are cared for, the translation of shepherd normally presents no difficulty. However, in those parts of the world where domestic animals such as sheep and goats wander freely as scavengers, there may be no term for shepherd, and the practice of tending such animals is largely unknown. Even in some parts of the world where sheep are raised, a shepherd is a person sent out to look after the sheep because such a person is either too young or too incompetent to do more serious tasks. Therefore it is essential in any situation to consider the connotations attached to the local practice of shepherding. In this verse the shepherd is The LORD, and the best translations may be the ones suggested in the comments on the title.

I shall not want: the verb means to lack, to be without, not to have (see 8.5, where the verb means “be less”). New Jerusalem Bible and New Jerusalem Bible have “I lack nothing”; New International Version “I shall not be in want.” Knox‘s rhetorical question is effective: “how can I lack anything?” The use in English of the verb want (Revised Standard Version, New American Bible, New English Bible) can be misunderstood, since the usual meaning of “to want” is “to desire.”

In some languages it will be necessary to make clear the relation between Yahweh being one’s shepherd and the consequence of not lacking anything; for example, “Because the LORD is my shepherd, I shall not lack anything” or “The LORD is the one who watches over me; therefore I shall have need of nothing.”

Quoted with permission from Bratcher, Robert G. and Reyburn, William D. A Handbook on the Book of Psalms. (UBS Helps for Translators). New York: UBS, 1991. For this and other handbooks for translators see here .