SLAM Information Governance group Clinical Data Linking Service (CDLS) will act as the Trusted Third Party. A bespoke dataset will be pulled within LDN and transferred to CDLS via the NHS 3N network. The BRC-ID, a pseudonymised identifier, links to patient identifiers in a secure database outside CRIS accessible to CDLS. Using identifiers present in both datasets CDLS will attach appropriate BRC-IDs to LDN cases known to CRIS. A column containing an anonymised ID that applies to all LDN cases will be created ("LDNID"). All identifying data in LDN will then be destroyed. This "new" dataset will be stored securely on a CDLS server behind the SLAM firewall. For approved projects researchers will send CRIS data to CDLS who will pull in LDN data linked by the BRC-ID to create a project-specific dataset, each case having a project-specific ID. The BRC-ID then removed, the final dataset becomes fully anonymised. [1] CRIS patients with an SMI diagnosis & a Lambeth GP will be identified and compared to LDN patients on the SMI case register. We will describe factors associated with having care from only one service or joint care. [2] A cohort of SMI patients known to both services in 2009 will be established. Physical healthcare received 2009-12(e.g. diabetes, smoking cessation, screening for cervical cancer) will be compared with other LDN patients. Individual, disease-related and systemic factors associated with both good and poor physical healthcare will be identified. [3]New cases of SMI on CRIS will be examined for information on physical illness and prescribed medications. This will be compared to that in LDN. LDN and CRIS data will be used to assess the effect of incomplete information on physical health in CRIS. Application: Our results will generate potential interventions, both clinical and at policy level. Our collaboration means these could be quickly implemented locally. Repeated linkages will allow the results to be observed almost in 'real time'.