Methods for preparing solid formulations of immunoglobulin single variable domains are provided. The methods are based on contacting solid carrier(s) with a liquid comprising the immunoglobulin single variable domains, e.g. by spraying the liquid onto the solid carrier(s), to cause granulation or coating of the carrier(s). During contacting the carrier is agitated, e.g. in a fluid bed, and the mixture of carrier and liquid is exposed to heat, e.g. a heated air stream, to evaporate the liquid.
