Joint attention (JA) is the purposeful coordination of an individual's focus of attention with that of another and begins to develop within the first year of life. Delayed, or atypically developing, JA is an early behavioural sign of many developmental disabilities and so assessing JA in infancy can improve our understanding of trajectories of typical and atypical development. This scoping review identified the most common methods for assessing JA in the first year of life. Methods of JA were divided into qualitative and quantitative categories. Out of an identified 13,898 articles, 106 were selected after a robust search of four databases. Frequent methods used were eye-tracking, electroencephalography, behavioural coding, and the Early Social Communication Scale (ECSC). These methods were used to assess JA in typically and atypically developing infants in the first year of life. This study provides a comprehensive review of the past and current state of measurement of JA in the literature, the strengths and limitations of the measures used, and the next steps to consider for researchers interested in investigating JA to strengthen this field going forwards.