In this groundbreaking monograph, Dr Randal H. Ackland offers a comprehensive analysis of glossolalia as discussed and described in the Pentecostal periodical literature that comes from the first generation of Pentecostal writers. Beginning with an overview of the scholarly literature devoted to glossolalia from inside and outside of the Pentecostal and Charismatic traditions, Ackland devotes the lion's share of his space to a detailed examination of the early Pentecostal documents themselves. Dividing the journals into Wesleyan-Pentecostal and Finished work streams, Ackland allows the theological categories to arise naturally from the documents. Having identified the major theological rubrics that emerge from this historical theological engagement, the author then places the results of his investigation into early Pentecostal reflection into dialogue with the work of major contemporary scholars to offer a constructive Pentecostal theology of glossolalia. The monograph includes an appendix that surveys the phenomenon of tongues speech throughout the history of the Christian church. This work is destined to be must reading for all future researchers working on the topic of Pentecostal glossolalia.Randal H. Ackland (PhD, Bangor University) is the Lead Pastor of Crossroads International Church (AG) in South Attleboro, MA, USA.