This study aims to develop and test a scale of internet interactive capability(IIC) in the context of communications and interactions between libraries and their readers. The scale of IIC is a formative scale composed of four dimensions, namely interactive orientation, IT technical capability, IT personnel capability, and capability of using internet interactive technologies, with each of the dimensions being a multiple-item reflective scale. By analyzing a survey data collected from 126 libraries, this paper tests the scale and provides the scale with evidence of reliability, face validity, content validity, convergent validity, discriminant validity, and nomological validity. This scale may serve as a basis for future studies on the antecedents, consequences and formation mechanism of IICs.