TIMSS (Trends in International Mathematics and Science Study) is a long-standing international assessment of mathematics and science at the fourth and eighth grades that has been collecting trend data every four years since 1995. About 70 countries use TIMSS trend data for monitoring the effectiveness of their education systems in a global context, and more countries join TIMSS with each subsequent assessment cycle. Because it marks the successful transition to its first fully digital assessment cycle, TIMSS 2023 is a watershed cycle in the 28 year history of TIMSS. Half the TIMSS countries pioneered the transition to digital assessment in TIMSS 2019 paving the way for an "all digital" turning point in TIMSS 2023. Capitalizing on the benefits of technological advances is necessary for TIMSS to remain in sync with global realities, and TIMSS 2023 will set the wheels in motion to improve the quality of TIMSS data, increase efficiency in data collection, and make the data more useful. To provide deeper insights into how students approach mathematics and science assessment tasks, solve problems, and communicate their responses, TIMSS 2023 will include more complex and innovative item types that capture both responses and process indicators. A digital item designer and translation system will support TIMSS 2023 item development, enabling interactive opportunities and provision of various digital tools for students to use in developing and providing their responses. The idea of Problem Solving and Inquiry (PSI) Tasks introduced in TIMSS 2019 (ED596167) will be further developed. PSI tasks are based on attractive, interactive scenarios that allow students to follow a series of steps toward a solution or goal. A variety of PSI tasks will be integrated into the mathematics and science assessments. Finally, a concerted effort will be made to increase the degree of automated scoring to improve scoring accuracy and comparability across countries, including research into using machine learning to evaluate graphical and short written responses.