Protein mixtures are essential ingredients in a multitude of natural and synthetic complex systems, such as the eye lens, the blood stream, the cytoplasm of living cells, yoghurt, and so forth. Research on protein interactions is thus pivotal to gain insight in the stability of such soft matter systems, in their structural and dynamical properties, and in their (biological) function. As nearly all of the current work focuses on interactions in relatively simple model systems (i.e., mixtures of either identical or like-charged proteins), this project will deal with cluster, glass, and crystal formation in concentrated protein mixtures of opposite charge. The project is highly original and proposed at an ideal time in the development of the field. In spite of considerable community interest, no systematic study, using (recently developed) suitable instrumental techniques and in close alliance with several European scientists who develop theory and simulations of the model systems, has been undertaken. This provides the community with a unique opportunity to link an excellent female researcher (MSc and PhD degrees were awarded cum laude) with an ideal background and proven ability to collaborate with an institution that has made major strides in this area of emerging interest and can provide the applicant with the necessary infrastructure and expertise to make this project work. As outlined in the following, the IEF fellowship will allow the applicant to gain additional scientific competencies and skills, to consolidate and extend her presentation and language skills, and to acquire additional and complementary management and leadership competencies and skills. Hence, this project will have a significant impact on the applicant’s future career prospects who is aiming to reach a position of professional maturity, diversity, and independence as her long-term goal is to establish an independent line of research within Europe in the field of life sciences.