Large language models (LLMs) are being deployed in high-stakes settings, but generating harmful or toxic content is a major concern.A data-centric pretraining framework is proposed to address this challenge by incorporating safety measures from the start.Key contributions include a safety classifier, a large synthetic safety dataset, and Harmfulness-Tag annotations to flag unsafe content.The safety-pretrained models successfully reduce attack success rates and maintain performance on standard LLM safety benchmarks.