Introduction

The Seven Stems Method teaches you to conjugate irregular verbs the same way you conjugate regular verbs: by adding the ending to the stem. The only difference is that irregular verbs have more than one stem!

For example, the verb conocer has two stems: conoc- and conozc-. Here is its conjugation table:

conoc- is a regular ER stem. conozc- is a Yo stem, which is one of seven types of irregular stems. The pink conjugation card above shows which tenses use a Yo stem and the endings to use with each tense.

Conjugation Tables

The regular AR, ER, or IR stems also have conjugation cards. So to construct the conjugation table for a verb, just plug the verb's regular stem into its regular conjugation card, then plug any irregular stems into their irregular conjugation cards and lay them on top.

Here is another example: valer has a regular ER stem val-, a Yo stem valg-, and a Future stem valdr-. Every verb form in this table uses one of these three stems plus the ending from that stem's conjugation card.

These conjugation tables cover the seven simple tenses. The compound tenses (e.g. he conocido, había ido) and imperative are derived mechanically from these. So to conjugate any irregular verb in Spanish in any tense, you just need to know which stems the verb has and which endings to use with each type of stem. What remains are a handful of spelling rules and a manageable number of true exceptions.

Stem Formulas

A verb's conjugation table can be compressed into a stem formula showing one example form for each stem the verb uses. For example, the stem formula for valer is:

This tells you what valer's ER, Yo, and Future stems are, respectively. If you know the conjugation cards for these stem types, then this is all you need to know to conjugate valer.

salir is similar to valer, except it is in IR verb and has one exception. So its stem formula is:

This is all you need to know to conjugate salir. You don't need to memorize its conjugation table: just know its two irregular stems and when to use them and remember to use sal in the imperative tú ("sal de ahí!").