I've always considered Dobbelaere's work on secularisation quite solid, but this early--but classic and often-cited--work is shaky. It's a 'trend report', which explains the expository nature of the book/journal special issue. But the fact is that the use of 'laicization', which Dobbelaere insists should be used to clarify the different levels of secularisation, only confounds them. Published in 1981, there are some useful summaries of early discussions, but overall this is rather a curiosity for those interested in the history of secularisation theory, not a very useful to contemporary discussions.