Provide a supplemental reading for each unit in your social studies curriculum. For example, for the social studies unit that focuses on World War II, have your students read the "Diary of Anne Frank" or another book that is relevant to the current unit. Tying the book into what you are teaching will not only reinforce the students' reading comprehension skills, but will help them understand the social studies aspect of it better as well.
Have students read the chapters of the social studies book aloud during class. Each day, during the social studies portion of class, instead of you reading the chapters to the class while they follow along, you can pick several students to alternate reading portions of the text, or you can go in order, having each student read a paragraph or two until you are finished with that day's section. Having the children read will help them with their reading skills and their comprehension skills, and will also encourage them to follow along with the text, whereas they might lose concentration and not pay attention if the teacher is the only one reading.
Have students organize their learning by having them create chapter outlines for each chapter to help improve their reading comprehension. Creating chapter outlines will teach them how to read the text closely and also how to determine the most important points of each chapter. Also, have them complete reading-related classroom activities such as creating word webs or word walls to help them learn vocabulary. Word webs and word walls are the same thing and are diagrams designed to help students connect ideas and to help them build connections with important words. An example of a word web would be having a main, central theme located in the middle of the paper, like "Civil War." Then, branching out from that central theme would be several other important words related to the Civil War such as "Abraham Lincoln," "Slavery," "Confederates," Union," etc. Then, branching off of each of these words would be even more words that are related to them, and so on, until the entire page is filled with a huge web of connected words and ideas.
Hold weekly vocabulary quizzes for the students using only social studies-related words. This will strengthen their vocabulary for words they may not be familiar with and will encourage them to read more thoroughly.