The present disclosure is directed to solid and salt forms of inhibitors of the CBP/p300 family of bromodomains made up of salts and crystalline forms of Formula (I). The compounds can be useful in the treatment of disease or disorders associated with the inhibition of the CBP/p300 family of bromodomains. For instance, the disclosure is concerned with compounds and compositions for inhibition of the CBP/p300 family of bromodomains, methods of treating diseases or disorders associated with the inhibition of CBP/p300 family of bromodomains (e.g., certain forms of cancer), and methods of synthesis of these compounds.