This research explores from what organisational experiences and developments the Balearic Islands’ Spatial Data Infrastructures could benefit from Catalonia’s SDI. Four case studies are the basis of the research: the SDI of Catalonia (IDEC), the SDI of the Balearic Islands (IDEIB), the SDI of Mallorca (IDEmallorca) and the SDI of Menorca (IDEmenorca). The purpose of this research is because the Balearic Islands’ autonomous region is a subnational entity in the early phase of building a SDI. The archipelago is taking its first SDI steps and affronting the challenges that this supposes. Considering the IDEC won the eSDINet+ 2009 best practice award and because of the cultural and physical closeness the IDEC is considered the best SDI node from which the Balearic Islands SDI nodes could benefit from. However, there is also the danger of just copying the IDEC case. Further, there’s consideration of the uniqueness of each case study. Besides, it’s known the experience of one case leads to dilemmas because the nature of assessing SDIs is nontrivial. Therefore, during the research, there’s been consideration about the non-trivial aspects of the SDI assessment. The three important features considered in the non-trivial issue of SDIs are: ambiguity, multi-faceted nature and non-trivial SDI assessment with the need to cope with risk. The case study investigation method was performed for three reasons. First, to learn about the organisational status. Second, to answer “how” and “why” questions. And, third, it is an appropriate way to research the sub-national SDIs in the Balearic Islands and Catalonia. The responsibilities of all the case studies are to make the spatial information accessible for all the users. Then, the roles of all the case studies are public information distribution, link from IDEE to their node and participant in the IDEE. Among other organisation aspects the triangular organisational structure and the maturity matrix were investigated and analysed. Through the surveys it was found out there are various similarities and differences between the Balearic Islands’ and the Catalan triangular organisation structure and other organisational aspects. The IDEC, created in 2001, and the IDEIB, that began in 2007, are at the network GII stage and at the “internetwork” stage, respectively. Both have a similar triangular organisation structure based on their responsibilities. Further IDEmallorca, which started in 2008, is at the intermediary GII stage, and IDEmenorca, which also began in 2008, is at the exchange GII stage. Besides, both follow a similar triangular organisation pattern. After performing a SWOT analysis of the cases studies based on the eSDI-Net+ indicators and the survey answers it is possible to affirm the Balearic Islands SDI nodes have a series of common strengths. These common strengths are: enable value adding services, existing Geoportal and view services, openness with data services (WMS), processes to assess SDI use and user satisfaction, service performance measurements, training provided to staff, legal status of the SDI node organisations and SDI related documentation in Catalan. Then, the weaknesses that all the Balearic Islands SDI nodes need to solve, according to this research, are the lack of strategy and technology and data problems. Also, the IDEmallorca and the IDEmenorca need to solve the following constraints: lack of support of the Councils to the SDI node, inadequate resources and insufficient awareness, poor perception and lack of commitment. To solve these constraints the Balearic Islands SDIs can benefit from the experiences and developments of the IDEC. These experiences and developments are thirteen: learn from other experiences; importance of encouraging local entities; coordination and collaboration between the regional and local entities; sectorial approach; support of the SDI in the organisation; raise awareness on SDI benefits; more partnerships; digital information available; focus on end-users; system engineering point of view; consider project environment; eGovernment funding; total investment paid back in 6 months.