Level 1 · Assumes nothing
Explains what BPD is, defines every term, and assumes no prior contact with therapy. Its job is orientation. It typically stops short of asking you to do much, which is appropriate and also its ceiling.
Books get labelled for beginners or for people further along, and the labels are usually about the reader's knowledge. The more useful question is what a book assumes you can already do — which is a different axis, and the one that actually determines whether it helps.

Not by how much you know. By what a book expects you to be capable of while reading it.
Explains what BPD is, defines every term, and assumes no prior contact with therapy. Its job is orientation. It typically stops short of asking you to do much, which is appropriate and also its ceiling.
You know roughly what is happening and want tools. Terms are still explained, and the book expects you to practise between chapters. Where this book sits.
Expects you to already have distress tolerance and to be applying it. Works on the harder ground: identity, long-term relationships, meaning, sustaining change over years. The last third of this book reaches into this.
Written for practitioners or for readers who want mechanism and evidence rather than instruction. Denser, referenced, and not designed to be used on a bad night.
Five questions, and the first one that gives a clear answer is your answer.
If not, level 1 first — or the first seven chapters here, which do that job before anything is asked of you. Starting with skills while the basic picture is missing means every technique arrives without a reason attached.
If not, that is the skill to build before anything else, and it is level 2 material. Everything downstream depends on noticing in time, and no advanced technique compensates for missing the window.
If not, you want level 2 regardless of how much you know. Knowing about TIPP is not the same as having it automatic, and a great many well-read people are stuck exactly here.
Then level 3 — values, direction, relationships over years, meaning. This is where the later chapters of this book live, and where most level 1 and 2 books have nothing left to say.
Level 4, and a different shelf. A trade book is not going to satisfy that, and this one does not try.
Mostly from people worried about being at the wrong one.
It works as a first book. Every term is explained where it appears and no prior therapy is assumed. It moves faster than a pure introduction, and the first seven chapters do the orientation work before any skill is asked for.
The mechanism chapters may cover ground you have. The later third — routines, relapse, the year-long integration plan, meaning — is where well-read readers usually report finding something new, because that material is rarer than skills material.
Not much, and less than people fear. The chapters are largely self-contained, so a mismatch costs you a chapter rather than the book. Starting with what is loudest now is generally better advice than starting at page one.
That usually means capacity rather than knowledge — reading anything is hard when things are bad. The audiobook is frequently the answer to this rather than a simpler book.
Sequentially, over a long period, yes. In parallel, no. The most common outcome of reading three BPD books at once is a good working knowledge and no practice.
Maintenance, mostly, and it stops looking like reading. Chapter 21 on sustaining recovery and chapter 25's year-long plan are what that stage actually consists of.