This dissertation looks at the lenition of intervocalic voiced fricative in Icelandic, arguably the most pervasive connected speech process in the language. These processes have been referred to as sloppy speech or slurring processes. I adopt an integrated approach to investigate the effects of linguistics, stylistic/discourse, and socio-indexical factors that have been associated with greater lenition. Additionally, I investigate (i) whether lenition reflects a gradient or categorical restriction in constriction degree, (ii) the relationship between acoustic deletion and articulatory reduction, and (iii) the relationship between reduction in constriction degree and duration. I address these questions with three empirical studies. I use both naturalistic data from corpora and controlled experimental data from an articulatory study and an acoustic production study. These three studies allow me to look at these multifaceted factors and their interactions. Overall, the results provide evidence that lenition is an intricate process involving the interaction of linguistics and stylistic/discourse factors. Their effects depend on the speaker and fricative constriction in question. Longer durations are associated with greater constrictions. Lenition mainly appears as a gradient reduction in constriction degree but there are indications of categorical distributions. Most instances of acoustic deletions still show articulatory gestures. However, some examples do not appear to show a fricative constriction, signifying either the endpoint of reduction or the lexicalizations of word plans without a fricative gesture. A speaker-by-speaker analysis reveals robust speaker specific differences that do not line up with the socio-indexical factors investigated. The results indicate that this is not a change in progress but a change that has already happened.