Title: Shared Knowledge Lifelong Learning. Abstract: In Lifelong Learning (LL), agents continually learn as they encounter new conditions and tasks. Most current LL is limited to a single agent that learns tasks sequentially. Dedicated LL machinery is then deployed to mitigate the forgetting of old tasks as new tasks are learned. This is inherently slow. We propose a new Shared Knowledge Lifelong Learning (SKILL) learning paradigm, which deploys a population of LL agents that each learn different tasks independently and in parallel. After learning their respective tasks, agents share and consolidate their knowledge over a communication network, so that, in the end, all agents can master all tasks. Our approach relies on a frozen backbone embedded in all agents at manufacturing time, so that only the last layer head plus some small adjustments to the backbone beneficial biases are learned for each task. To eliminate the need for a task oracle, agents also learn and share summary statistics about their training datasets (Gaussian Mixture Clusters), or share a few training images, to help other agents assign test samples to the correct head using a Mahalanobis task mapper. On a new, very challenging dataset with 102 image classification tasks, we achieve significant speedup over 18 LL baselines (e.g., >9,000x speedup over single-agent EWC) while also achieving higher (and SOTA) accuracy.