The present paper provides an overview of articulatory complexity and articulatory difficulty in speech production, with a focus on their relevance to acquisition, sound change, and disordered speech. These constructs are important because structures described as articulatorily complex often show distinct production patterns: they may be acquired later, produced less accurately by speakers with speech disorders, or be more susceptible to diachronic change. However, understanding when articulatory complexity has an explanatory role in speech production requires not only assessing degrees of complexity but also determining when complex movements result in articulatory consequences. Researchers have operationalized articulatory complexity in several ways, but existing metrics do not always yield the same predictions. This paper reviews major approaches to establishing articulatory complexity and evaluates commonly used complexity scales. Particular attention is given to the limitations of these scales, especially when they are interpreted as measures of articulatory difficulty. The review concludes by examining experimental methods for assessing articulatory difficulty more directly. I argue that such methods provide a more reliable basis for establishing the relationship between complexity, difficulty, and observed production patterns.