For regular verbs, the past participle is the same as the simple past tense. That means you simply add –ed to the end.
[main verb] walk
[past participle] walked
Just like with the present participle, there are special rules for verbs that end in -c, -e, or a consonant and –y, as well as for words ending in one vowel and one consonant.
For verbs ending in -c, you first add a –k before –ed.
For verbs ending in –e, add only –d.
For verbs ending in a consonant and –y, replace the –y with an –i before adding –ed.
For verbs ending in one vowel and one consonant, double the consonant before adding –ed.
Just like with present participles, if a word ending in a single vowel and single consonant has two syllables but the second syllable is not stressed, you add –ed without changing anything.
The hardest part about past participles is irregular verbs. Many irregular verbs have unique past participles that don’t follow the normal rules. Unfortunately, you just have to memorize each irregular verb and its special past participle.
[irregular verb] see
[past participle] seen
[irregular verb] do
[past participle] done
Feel free to review our complete list of irregular verbs, which includes their correct past participles.