Despite the lack of structure, there are certain themes running through the Book that reappear at various points. The New Oxford Annotated Apocrypha identifies ten major recurring topics:

1. The Creation (16:24–17:24, 18:1–14; 33:7–15; 39:12–35; and 42:15–43:33);
2. Death (11:26–28; 22:11–12; 38:16–23; and 41:1–13);
3. Friendship (6:5–17; 9:10–16: 19:13–17; 22:19–26: 27:16–21; and 36:23–37:15);
4. Happiness (25:1–11; 30:14–25; and 40:1–30);
5. Honor and shame (4:20–6:4; 10:19–11:6; and 41:14–42:8);
6. Money matters (3:30–4:10; 11:7–28; 13:1–14:19; 29:1–28; and 31:1–11);
7. Sin (7:1–17; 15:11–20; 16:1–17:32; 18:30–19:3; 21:1–10; 22:27–23:27; and 26:28–28:7);
8. Social justice (4:1–10; 34:21–27; and 35:14–26);
9. Speech (5:6,9-15; 18:15–29; 19:4–17; 20:1–31; 23:7–15; 27:4–7; 27:11–15; and 28:8–26); and
10. Women (9:1–9; 23:22–27; 25:13–26:27; 36:26–31; and 42:9–14).

The Wisdom of Sirach is a collection of ethical teachings. Thus Ecclesiasticus closely resembles Proverbs, except that, unlike the latter, it is presented as the work of a single author, not an anthology of maxims drawn from various sources, presented in verse form. The question of which apothegms actually originated with Sirach is open to debate, although scholars tend to regard him as a compiler or anthologist.

The teachings are applicable to all conditions of life: to parents and children, to husbands and wives, to the young, to masters, to friends, to the rich, and to the poor. Many of them are rules of courtesy and politeness; and a still greater number contain advice and instruction as to the duties of man toward himself and others, especially the poor, as well as toward society and the state, and most of all toward God.