The present invention relates to certain compounds (e.g., imidazopyrazine, imidazopyridine, imidazopyridazine and imidazopyrimidine compounds) that act as inhibitors of the MAP kinase interacting kinases MNK2a, MNK2b, MNK1a, and MNK1b. The present invention further relates to pharmaceutical compositions comprising these compounds, and to the use of the compounds for the prevention and treatment of diseases (e.g., proliferative diseases (e.g., cancer), inflammatory diseases, autoimmune diseases, metabolic diseases, and neurodegenerative diseases (e.g. autism, autism spectrum disorders, Alzheimer's disease)), as well as methods of treating these diseases.