Sub-seasonal to seasonal (S2S) predictions are rapidly filling up the gap between the weather and climate predictions in the operational suites. Tropical-extratropical interactions, sea-ice, soil moisture, stratosphere-troposphere interactions have emerged as untapped sources of predictability on the S2S time scales. An extensive database of S2S forecasts and reforecasts from operational centers has been created by the WWRP/WCRP S2S project that enables these sources of predictability to be studied, forecast skill assessed, and early warning systems developed. Contributions are solicited on recent advancements in assessing the predictability on S2S time scales, S2S prediction skill and remaining challenges with emphasis of making use of the S2S database, and development of metrics for measuring the success of forecasts in ways that are useful to stakeholder communities.