ながらに / ながらの

ながらに and ながらの mean "just as it was", "in that state": something is done, or exists, without the state it started in changing. They attach to a noun or a verb's ます-stem, but only to a handful of words, and each combination is learnt as a phrase. ながらに describes how something is done; ながらの goes before a noun.

The fixed phrases

The words that take it are few: むかし昔, なみだ涙, うまれ生まれ, い居 and いつも cover nearly every case you will meet. むかしながら昔ながらの "traditional" and いつもながら "as always" belong to everyday speech and advertising; the rest are written or formal.

With 生まれ and 居, ながらに often takes して, which adds weight but no meaning.

ながらに or ながら

Everyday ながら joins two actions done at once, and any verb takes it. ながらに describes a state that stays as it is, and only the words above take it.

• × テレビを見ながらに勉強する → テレビを見ながら勉強する