Text frame vertical justification

Well... the internet is the very defintion of solutions that are simple, easy to understand, and wrong. A good part of the traffic we get here is from novices and even moderately experienced users who have been led down some garden path by a video, blog, tutorial or how-to from a source that has less than sterling understanding. 🙂

Yes, vertical justification will give you even bottom margins, at the cost of having no two pages with aligned text lines. One of those cases where the "fix" is often worse than the original problem, as uneven line spacing is one of the subtle layout flaws can make a book tiring and annoying to read.

There is no really simple method to get even line spacing and even mostly even bottom lines; it all starts from careful layout beginning with the text spacing, text frame height, and keeping the spacing for everything but body text even multiples of the base leading (spacing). ID has tools to help but in the end it's one of the pinnacles of typographical design to get it all right.

I am not sure if there's a good tutorial out there on this, as it's complex and the topic of whole books (if not bookshelves). But here's the basics, and they start right from the first page layout and style definitions—

• Choose a body font size and leading, such as 10/12 (10pt type on 12pt spacing/leading).
• Set your primary text frame to be some even multiple of that leading. (For a 9-inch tall page, for example, with an 8-inch vertical text frame, you'd want an even multiple of 12 points, or 576pt, or 48 picas... all of which happens to be 8 inches, but if you use different page size or top/bottom margins you have to make this adjustment to be exact multiples of your leading.)
• In Edit | Preferences | Grids, set the Baseline Grid to Increment by 12 points, relative to Top Margin (of the text frame). (Be sure "Grids in Back" is checked so the grid lines don't obscure your content.)
• In View | Grids & Guides, Show Baseline Grid. You should now have pale blue lines in your text boxes that exactly fill it, with the last one right on the bottom margin. (If not, you need to adjust the text frame height as above.)
• Starting with your base BODY text style, under Indents and Spacing, set Align to Grid to All Lines.

Okay, now all of your BODY text and anything derived from/based on it should snap to the baseline grid. With very simple text, that will be all that's needed; all the pages should be lined up with the same text spacing and an even bottom line on full pages.

That's Step 1. Sorry.

For every style that interrupts steady body text, you have to adjust the line height/leading and space above/below to exactly snap to your baseline grid. A heading, for example, might be 14 points and thus need to be given a 24pt leading, with any space above or below added in 12pt increments. That way it will take up exactly the height of 2 or 3 or 4 text lines, and everything remains in lockstep with the baseline grid.

Repeat for all paragraph styles and hierarchies of them.

That's most of Step 2.

From here, you just have to keep adjusting your text, sometimes tucking in orphan lines or even extending a large paragraph by one line to get all the pieces to align, working forward only — align pages 2-3, move on. Don't work forward and back because the adjustments are cumulative and forward and "fixing" something on page 24 will mess up all your work on pages 25-on.

Yes, it's tedious. Yes, it's fussy. No, there is not any good way to automate all of it, and you need to master all the tools for tweaking and tucking paragraph length and line count to make it easy.

There's an advanced method in which you set the Baseline Grid at half leading  —6 points in this case — which gives you a little more flexibility over the spacing and esthetics for headings, etc., but it brings a list of its own problems. Just throwing that out if you want to experiment; it can be very powerful (and I'm laying out a complex textbook using the half-height method right now).

Happy to answer more questions, but know that this is a method and skill that really only comes with experimetnation and practice. Once you grasp the basics, we can move on to those methods for subtly tweaking paragraphs and doing things like offsetting headings to get around awkward spacing settings.