An interlayer comprising: a first poly(vinyl acetal) resin; a second poly(vinyl acetal) resin having a residual hydroxyl content that is at least 2 weight percent higher or lower than the residual hydroxyl content of said first poly(vinyl acetal) resin; at least one plasticizer, wherein each plasticizer present in said interlayer has a refractive index of less than 1.460; and a refractive index balancing agent, wherein said RI balancing agent includes residues of a high RI aldehyde having a refractive index of at least 1.421 as measured by ASTM D542 at a wavelength of 589 nm and a temperature of 25°C, and wherein said first poly(vinyl acetal) resin comprises at least 0.5 weight percent of said residues of said high RI aldehyde, based on the total weight of aldehyde residues of said first poly(vinyl acetal) resin, wherein each of said first and second poly(vinyl acetal) resin are present in said interlayer in an amount of at least 0.5 weight percent, based on the total weight of resins in said interlayer, and wherein said interlayer has a haze value of not more than 5 percent, and wherein said interlayer comprises a multilayer interlayer having at least a first resin layer and a second resin layer adjacent to said first resin layer, wherein said first resin layer comprises said first poly(vinyl acetal) resin and said second resin layer comprises said second poly(vinyl acetal) resin, wherein said RI balancing agent is present in at least one of said first and said second resin layers, and wherein the absolute value of the difference between the refractive index of said first resin layer and the refractive index of said second resin layer is not more than 0.010. a first poly(vinyl acetal) resin; a second poly(vinyl acetal) resin having a residual hydroxyl content that is at least 2 weight percent higher or lower than the residual hydroxyl content of said first poly(vinyl acetal) resin; at least one plasticizer, wherein each plasticizer present in said interlayer has a refractive index of less than 1.460; and a refractive index balancing agent, wherein said RI balancing agent includes residues of a high RI aldehyde having a refractive index of at least 1.421 as measured by ASTM D542 at a wavelength of 589 nm and a temperature of 25°C, and wherein said first poly(vinyl acetal) resin comprises at least 0.5 weight percent of said residues of said high RI aldehyde, based on the total weight of aldehyde residues of said first poly(vinyl acetal) resin, wherein each of said first and second poly(vinyl acetal) resin are present in said interlayer in an amount of at least 0.5 weight percent, based on the total weight of resins in said interlayer, and wherein said interlayer has a haze value of not more than 5 percent, and wherein said interlayer comprises a multilayer interlayer having at least a first resin layer and a second resin layer adjacent to said first resin layer, wherein said first resin layer comprises said first poly(vinyl acetal) resin and said second resin layer comprises said second poly(vinyl acetal) resin, wherein said RI balancing agent is present in at least one of said first and said second resin layers, and wherein the absolute value of the difference between the refractive index of said first resin layer and the refractive index of said second resin layer is not more than 0.010.