A well-developed body paragraph usually contains at least three to five sentences. However, the number of sentences can vary depending on the complexity of the topic and the amount of detail required to fully develop the paragraph. A good body paragraph should have a clear topic sentence that introduces the main idea of the paragraph, supporting sentences that provide evidence or examples to support the main idea, and a concluding sentence that summarizes the paragraph and transitions to the next. Well-developed body paragraphs are an important part of any essay or written work, as they help to organize ideas and provide a clear and coherent structure for the reader.