The phrase "is instrumental" is often used to indicate that something or someone is essential or crucial to a particular outcome. Synonyms that convey a similar meaning include pivotal, critical, indispensable, key, vital, significant, fundamental, important, necessary, and integral. These words all indicate that something or someone plays a central role in achieving a particular goal or outcome. Other synonyms for "is instrumental" might include "plays a key role," "is an essential part of," "is crucial in," "is necessary for," or "is an integral component of." Whatever the specific phrasing, these words indicate the importance of a particular element in achieving success or achieving a particular outcome.