にしたがって

にしたがって has two meanings. After a verb of change in the dictionary form, it means "as": as one thing changes, another changes along with it. After a noun such as a rule or an instruction, it means "following" or "in accordance with".

It comes from the verb したがう従う, "follow, obey", and is often written にしたがって従って. にしたがい is the written form of both meanings.

"As": both sides change

In the "as" meaning, both halves describe a gradual change, and the verb at the end is usually one of change: なる, きごう〜てくる, きごう〜ていく, さがる下がる. A single event does not fit.

• × 駅に着くにしたがって、電話した → 駅に着いたら、電話した

にしたがって or につれて

In the "as" meaning, につれて says the same thing and the two can be swapped. Only にしたがって also means "following a rule or an instruction".

• × 説明書につれて組み立てた → 説明書にしたがって組み立てた