This master's thesis analyses the current regulation of 'land grabbing' by international human rights law and food security policies from a human rights perspective. The activities of relevant local organisations in target countries are also critically evaluated. 'Land grabbing', i.e. large-scale land investments violating human rights, is a recent and growing phenomenon with negative implications on food security and development in target countries. The findings of this master's thesis are based on literature analysis. Data were also derived from expert interviews with employees at Austrian NGOs and their partner organisations in Brazil and Tanzania. A major conclusion is that the enforceability and justiciability of human rights in a world dominated by political dynamics has been deficient. The coming into force of the Optional Protocol to the International Covenant on Economic, Social and Cultural Rights has been a first step into the right direction. In order to avoid conflicts of different human rights, a minimum level of each right should be respected. Human rights law should be prioritised over all other legal regimes. In addition, food security policies need to become more comprehensive, guided by human rights, and their implementation should be better monitored. These improvements need to receive political support from various parties such as states, corporations, and civil society organisations. Concerning Brazil and Tanzania, the work of local organisations shares various common features. Access to land and water as well as security of tenure are preconditions to improvements in agricultural methods. The organisations mainly conduct research, lobbying, legal aid and trainings for their target groups. In general, their struggle for improved tenure and food security is cumbersome. Despite achievements, the organisations have not been able to eradicate the structural causes of poverty in target countries, also related to land grabbing.