César Vallejo is one of the finest poets of Latin America, and his poetry has managed to maintain a broad readership base right up until the modern day. Since Vallejo's posthumous poems were first published in 1939 in an edition supervised by his widow, Georgette de Vallejo, there remain to this day a number of unanswered questions about them. In what order did Vallejo write the poems? Would he have published the poems as they are? This book, by a careful analysis of the evidence available, proposes a new chronology for the posthumous poems, suggesting that the Peruvian poet's work went through a number of crucial phases in the 1920s and 1930s, ranging from 'poesía comprometida' to non-committed, politically disillusioned poetry, before concluding in a set of fifteen poems dedicated to the Spanish Civil War which, against all the odds, fuse the best aspects of Marxism with the best of Christianity.