Understanding Society: the UK Household Longitudinal Study is the largest household panel study in the world which addresses the key scientific and policy questions of the 21st century. It collects high quality annual longitudinal data on individuals of all ages in households representative of the UK population. Such data enables researchers to explore the experience, causes and consequences of changes in people's lives - their family structure, health, income, expenditure, employment and housing - key issues for policy makers today. The Study also has additional samples that allow the detailed exploration of the circumstances of key immigrant and ethnic minority groups; and collects data on cognition, objective measures of health and genetics to understand how people's health and wider circumstances interact. Additionally, the Study invests in innovative ways of collecting data to continually improve the content and quality of data available. Overall, therefore, the Study enables the production of research to inform policy and practice. The Study was inaugurated in 2008 with an Innovation Panel to test methods and the first main wave of fieldwork in 2009. To date four waves of the main study and six waves of the Innovation Panel, as well as data collected from a nurse visit and derived from blood samples, are deposited in the UK Data Service. Data collection and planning are ongoing for Waves 5-8; this bid covers the costs of data collection for Waves 9-11 and associated activities. Based on careful experimental research and evaluation, in Waves 9-11 the Study will move to mixed mode data collection - meaning people will be able to complete the questionnaire face-to-face or online. This maximises flexibility for respondents, but given people may answer questions differently, depending on whether an interviewer is asking them or not, it creates complexities for data users. Crucial to our work will be to support data users to ensure they are able to use such complex data effectively. Policy and research agendas are constantly evolving, and it is important in a longitudinal study to balance creating long series of the same questions with including questions that address emerging topics and make effective use of new approaches to data collection. In this funding period, we will undertake a programme of innovation to bring in new technologies, enabling us to collect better data to address critical social science and policy issues. We will also work with Topic Champions to improve the content of the survey and the way we present the data to users. Supporting researchers in universities, government, third sector and businesses to use the data effectively is fundamental to the success of the Study. We will therefore invest in improving our user support for the Study and sharing the data in different ways to make them easier for different kind of users to analyse. We also have a Policy Unit that directly works with government departments and third sector organisations to ensure that they are fully aware of how Understanding Society data can be used to address their policy concerns and to help them do so where appropriate, and an Impact Fellow who supports both policy users and researchers to work effectively together to generate impact. During this funding period, as more waves of the Study are released to data users, the value of the study will increase significantly as it can be used to answer more questions about the effect of different kinds of changes on people's lives. We will create a wide range of opportunities for users to share their findings - for example at conferences and workshops, through Insights, by promoting publications and case studies on the website and through social media - and by creating an online community of users so that they can engage with each other.