In this essay, I propose to analyze the meaning of some of the interdictions and beliefs connected to magic and demonology in ancient Judaism by taking into account different sources from the Dead Sea Scrolls. Firstly, I provide a selective overview of passages belonging to normative, exegetical and ritual texts, in which the prohibition of necromancy, divination and incantatory practices is stemmed. These practices are not per se forbidden but when they are related to violations like apostasy, blasphemy, defilement of secrets and sexual transgressions. Afterwards, I consider some admitted rituals, finalized to divinatory, therapeutic and anti-demonic purposes. On some appointed days, maskilim, recognized sages and the whole community were engaged in their performance and achievement. In the final part, I attempt to shed light on the changes these traditions underwent outside the Qumranic context and at a later period by comparing the features of one of the exorcist formula used by the members of the community with a similar text from the middle Ages that was discovered among the Cairo Genizah manuscripts.